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  • 1975-1979  (2,433)
  • 1975  (2,433)
  • Polymer and Materials Science  (2,182)
  • Physics  (470)
  • Biochemistry and Biotechnology  (167)
  • Engineering General  (84)
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  • 1975-1979  (2,433)
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Keywords
  • 101
    Electronic Resource
    Electronic Resource
    Raman studies of the crystalline, solution, and alkaline-denatured states of β-lactoglobulin (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 649-662 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Raman spectra of β-lactoglobulin in the crystalline, freeze-dried, and solution states are compared. The spectra of the freeze-dried and crystalline proteins were practically identical. The conformationally sensitive amide III line appearing at 1242 cm-1 increased in intensity 30% upon dissolution of the protein in water which is interpreted as a conformational change in the disordered chains of the protein. This result appears to be a phenomenon for globular proteins containing a large disordered chain fraction.The alkaline denaturation of β-lactoglobulin was studied. When the pH was increased from 6.0 to 11.0, the amide III line shifted from 1242 to 1246 cm-1, broadened, and decreased in intensity. This is consistent with the conversion of β-sheet regions in β-lactoglobulin to the disordered conformation, as has been proposed by other investigators. At pH 13.5 the amide III shifts to 1257 cm-1 characteristic of a completely disordered protein, indicating that any remaining “core” of β-sheet has been randomized.Several changes in the intensities of the tyrosine and tryptophan vibrations accompany the denaturation. As the pH is increased from 6.0 (native state) to 11.0 (denatured state) the intensity ratio of two tyrosine ring vibrations, I855 cm-1/I830 cm-1, decreases from 1.0:0.9 to 1.0:1.3. The same ratio for a copolymer consisting of 95% glutamic acid and 5% tyrosine at pH 7.0, where the polymer forms a random coil exposing the tyrosine to the aqueous environment, is 1.0:0.62. This ratio more closely resembles that corresponding to β-lactoglobulin at pH 6.0 (native state) than pH 11.0 (denatured state) suggesting that the average tyrosine in the denatured state may be in a more hydrophobic environment than in the native state. A time-dependent polymerization of the denatured protein reported by other investigators and observed by us may account for the change in the tyrosine environment.A tryptophan vibration appearing at 833 cm-1 in the spectrum of the native state becomes weak as the pH is increased to 11.0. The intensity of this line may also reflect the local environment of the tryptophan residue.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140317
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  • 102
    Electronic Resource
    Electronic Resource
    Condensed states of nucleic acids. II. Effects of molecular size, base composition, and presence of intercalating agents on the Ψ transition of DNAPart I: Cheng and Mohr (1974)5. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 663-674 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism spectroscopy has been used to investigate the influence of DNA molecular size, base composition, and the presence of intercalating agents upon the Ψ transition of DNA brought about by high concentrations of poly(ethylene oxide) and salt (Lerman (1971) Proc. Natl. Acad. Sci. (U.S.) 68, 1886-1890). A molecular weight of 0.15-3.0 × 106 daltons yields maximum formation of Ψ-DNA. Both the amplitude of the large negative CD band at 265 nm - a chief characteristic of the Ψ state - and the thermal stability of Ψ-DNA increase linearly with increasing mole fraction of guanine plus cytosine in the DNA sample. Either ethidium or proflavine, at concentrations where approximately one dye is bound per 5-10 nucleotide residues, can prevent the transition completely. Striking similarities between the Ψ-DNA produced by poly(ethylene oxide) + salt and the complexes formed between DNA and lysine-rich histone f1 suggest the presence of similar nucleic acid-nucleic acid interactions in both types of condensed phase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140318
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  • 103
    Electronic Resource
    Electronic Resource
    Estimation of amino acid residue side-chain absorption in the infrared spectra of protein solutions in heavy water (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 679-694 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The values of maximum frequencies, intensities, and other spectral parameters of the main absorption bands of amino acid residue side-chain groups have been obtained in the 1500-1800-cm-1 region for solutions in heavy water at pD 1-12. It is shown that absorption of residues of asparagine, glutamine, aspartic and glutamic acids, arginine, and tyrosine must be taken into account in quantitative studies of the infrared spectra of polypeptide and protein solutions in heavy water. Examples of separating out the amide I band for ribonuclease A in heavy water are given.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140402
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  • 104
    Electronic Resource
    Electronic Resource
    Neutron-scattering spectroscopy of the α- and β- forms of poly-L-alanine. Motion of the methyl side chain (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 715-721 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Detailed inelastic, incoherent neutron-scattering (INS) spectra are presented for poly-L-alanine in both the α-helical and β-sheet form. Assignments are made from previous normal coordinate calculations. Of particular interest is the methyl torsion at 230 cm-1, which is the strongest peak in the spectrum and is independent of backbone conformation. The height of the potential barrier for methyl group rotation is calculated to be 14 kJ mol-1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140404
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  • 105
    Electronic Resource
    Electronic Resource
    Influence of the sugar configuration on the structure of RNA by conformational analysis of the ribose-phosphate unit (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 695-713 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformation of the ribose-phosphate unit for the four principal configurations of the sugar ring has been studied using the extended Hückel theory and the Lennard-Jones empirical potential. Initially, the oxygen atoms of the p3 and p5 groups were not taken into account. With this restriction, the energy of this residue with regard to the structure of RNA has been minimized for the rotational angles ψ and φ′.The equivalence of the sugar puckering C2′endo ≃ C3′exo and C3′endo ≃ C2′exo has been confirmed. We find that the role of the sugar configuration is important and that there is a difference in the rotations around the bond C3′-O3′ (φ′ angle) according to this configuration. The C3′endo sugar form seems to be energetically preferred for this residue of RNA.The oxygen atoms and the electrostatic interactions were then introduced into the empirical potential. The variation of the energy when varying φ′ for different positions of the p5 group was studied for the main C3′endo and C2′endo configurations of the sugar; in this condition the φ′ rotation is considerably restricted but the allowed regions continue to differ according to the configuration of the sugar considered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140403
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  • 106
    Electronic Resource
    Electronic Resource
    Studies on cyclic peptides. II. Synthesis of cyclic peptides containing sarcosine (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 723-731 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyclic peptides containing sarcosine, cyclo-(Pro-Sar-Gly)2, cyclo-(Sar-Sar-Gly)2, cyclo-(Sar4), and cyclo-(Sar6) have been synthesized by the cyclization of the p-nitrophenyl ester of linear peptides. The tert-butoxycarbonyl group was used as the Nα-protecting group, which was removed by acid. Benzyl ester was used to protect the C-terminal. tert-butoxycarbonylpeptide was obtained by the stepwise elongation of the peptide bond by the carbodiimide method. Deblocking and cyclization of the linear peptides gave the cyclic peptides.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140405
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  • 107
    Electronic Resource
    Electronic Resource
    Studies on cyclic peptides. III. The specific interaction of cyclic peptides with benzene and an application of the solvent-induced nmr shift to the conformational analysis of cyclo-(Pro-Sar-Gly)2 (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 733-747 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction between cyclic peptides [cyclo-(Sar4), cyclo-(Pro-Sar-Gly)2, cyclo-(Sar-Sar), and cyclo-(Sar-Gly)] with benzene has been investigated by nmr spectroscopy. The experiment with cyclo-(Sar4) showed that benzene interacted preferentially with the trans peptide bond in a similar manner to the dimethylformamide-benzene interaction. The solvent-induced nmr shift was then applied to the conformational analysis of cyclo-(Pro-Sar-Gly)2 with the aid of the molecular model. The major conformation was proved to possess the C2 symmetry with internally hydrogen-bonded glycine residues, in which all peptide bonds were trans. The interaction of cyclo-(Sar-Sar) and cyclo-(Sar-Gly) with benzene was also studied. The association constant was 0.115-kg solution per mole of cyclo-(Sar-Sar) and 0.089-kg solution per mole of cyclo-(Sar-Gly) in chloroform.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140406
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  • 108
    Electronic Resource
    Electronic Resource
    Investigation of the thermal unfolding of secondary and tertiary structure in E. coli tRNAfMet by high-resolution nmrThe results presented here were taken from the Ph.D. Thesis of K.L.W., submitted December, 1973. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 749-762 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high-resolution (300 MHz) proton nmr spectrum of E. coli tRNAfMet has been examined in 0.17M NaCl, with and without Mg2+, and at various temperatures. In light of recent studies of other E. coli tRNA and fragments of tRNAfMet, some low field (11-15 ppm) resonances previously assigned to secondary structure base pairs are reassigned to a tertiary structure A14-S4U8 base pair and a protected uridine residue in the anticodon loop. These two resonances and other low field resonances which are assigned to secondary structure base pairs are used to monitor the thermal unfolding of the molecule. In the absence of Mg2+ the tertiary structure base pair is present only to ∼45°C, but in the presence of Mg2+ it remains until at least 70°C. Analysis of the temperature dependence of other low field resonances indicates that the melting of the dihydrouridine stem occurs more or less simultaneously with the loss of tertiary structure. The observation of the resonance from the A14-S4U8 base pair proves that tertiary structure is present in this molecule below 40°C, even in the absence of Mg2+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140407
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  • 109
    Electronic Resource
    Electronic Resource
    Relaxation kinetics of the triple-stranded helix ⇄ coil transition at short chain length. A model including the staggering of chains (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 763-780 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relaxation kinetics of a staggering zipper model are presented, in which the formation of helical nuclei is regarded to be rate-limiting and in which the sliding of strands along the helices is prohibited. Instead a realignment of staggered chains is only possible via complete uncoiling. While maintaining the third order of the initial reaction as in an all-or-none mechanism, the model predicts a large range of relaxation times, which contribute to the mean relaxation time according to the stability of the individual species and which are weakly coupled in the range of small amounts of helical content. The model can easily be compared to experimental results and agrees well with relaxation data obtained from a triple-helical peptide fragment of collagen. It may be readily expanded to other multistranded helix ⇄ coil transitions with steady-state formation of the individual species and it suggests that the fraying of the helix ends is hidden by the fast-relaxation times due to the equilibration of the shortest helical species.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140408
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  • 110
    Electronic Resource
    Electronic Resource
    Spécificité de l'interaction DNA-platine dosage du platine, pH métrieUne communication préliminaire de cet article a été faite au Second International Symposium on Platinum Coordination Complexes in Cancer Chemotherapy, 16-18 avril 1973, Université d'Oxford, Angleterre. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 781-799 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction between the sodium salt of a DNA extracted from salmon sperm (41% GC) with [Pt(NH3)4]Cl2, [Pt(NH2—(CH2)2—NH—(CH2)2—NH2Cl]Cl, cis-Pt(NH2—(CH2)2—NH2)Cl2, cis-Pt(NH3)2Cl2, trans-Pt(NH3)2Cl2, K[Pt(C2H4)Cl3], and K2[PtCl4) indicates at least three types of complexation. A correlation is found between the change of pH and the number of platinum atoms fixed per (AT + GC) unit. The first binding site is located on the G-C pairs (guanine-cytosine), most likely the N-7(G) site, as it was shown in a previous study of the guanosine-platinum salts. The fixation of the second platinum atom by the pair (AT + GC) takes place with liberation of protons. In the case of the complexes cis-Pt(NH2—(CH2)2—NH2)Cl2, cis-Pt(NH3)2Cl2, and trans-Pt(NH3)2Cl2 the second interaction seems to involve simultaneously the N-7(A) and the N-1(G) and N-3(C) sites. This latter intercrosslink between guanine and cytosine obviously liberates protons and the decrease of pH is related in this case to the trans effect of the platinum compounds. The first two platinum atoms in the reaction of K2PtCl4] or the Zeise salt, K[Pt(C2H4)Cl3] with DNA are fixed on the G-C pairs. A maximum of six platinum atoms per (AT + GC) unit were fixed in this case. Preliminary experiments with a DNA extracted from bacteria Micrococcus lysodeikticus (72% GC) give similar results.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140409
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  • 111
    Electronic Resource
    Electronic Resource
    Optical property of bovine plasma albumin between 2 and 82 eVA part of this work was presented at the 4th International Conference on Vacuum Ultraviolet Radiation Physics, Hamburg, Germany (July 1974). (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 839-847 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical constants of bovine plasma albumin in the form of a dry solid film have been determined in the 2-82 eV region of photon energy. The extinction coefficient k was obtained by transmission measurements on thin films on a calcium fluoride substrate and on ultrathin films of polystyrene supported by mesh screen. The refractive index n was determined by a Kramers-Kronig analysis using the measured values of k. The complex dielectric function ε and the energy-loss function -Im(1/ε) for charged particles were derived from the data of n and k. The result for k exhibit, in addition to the well-known absorptions at 4.4, 5.5, and 6.4 eV, a small peak at 7.6 eV, a shoulder around 9.7 eV, and a strong peak at 14.0 eV. A prominent peak at 22.7 eV in the energy-loss function exhibits a large degree of collective nature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140412
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  • 112
    Electronic Resource
    Electronic Resource
    Equilibrium studies on neutral red-DNA bindingA preliminary account of this work was presented in September, 1974, at the 168th National ACS Meeting in Atlantic City, New Jersey. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 825-837 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectrophotometric binding studies were undertaken on the interaction of neutral red with native and heat-denatured, sonicated, calf thymus DNA in a 0.2M ionic strength buffer containing Tris-sodium acetate-potassium chloride at 25°C. The pKA of neutral red was found to be 6.81. At pH 5 the binding of protonated neutral red was complicated even at low concentration ratios of dye to DNA. In the pH range 7.5-8.5 the tight binding process could be studied and it was found that both protonated and free base species of neutral red significantly bind with DNA having association constants (in terms of polynucleotide phosphate) of 5.99 × 103 M-1 and 0.136 × 103 M-1, respectively, for native DNA and 7.48 × 103 M-1 and 0.938 × 103 M-1, respectively, for denatured DNA. The pKA value of the neutral red-DNA complexes were 8.46 for native DNA and 7.72 for denatured DNA. These results are discussed in terms of possible binding mechanisms.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140411
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  • 113
    Electronic Resource
    Electronic Resource
    Variations thermiques, entre 1 et 300°K, de la chaleur specifique de la L-alanine, tri(L-alanine), et de la poly(L-alanine) sous formes α et β (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 801-823 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat capacities of L-Alanine, tri(L-alanine), and poly (L-alanine) (α helicoidal form and β pleated sheet structure) have been measured between 1.5 and 300°K with a standard adiabatic calorimeter.In the solid state, the heat capacity is in general dut to three parts which are additive in first-order approximation. (1) The lattice vibrations or “acoustical modes” which are the largest at low temperatures. The low-temperature lattice specific heat is proportional to T, T2, or T3 for an ideal one-, two- or three-dimensional solid, respectively. (2) The so-called group vibrations or “optical modes” which, due to their high frequencies, usually take effect only at higher temperatures. (3) The defects and unharmonic effects.The α-amino acid and its trimer present a specific heat thermal variation characteristic of molecular solids which is correctly fitted with an empirical law proposed by Kitaigorodskii. This author assumes that, for such solids, the molecular lattice point has six degrees of freedom (three of translation and three of rotation). Thus the lattice contribution of the specific heat satisfies the Debye approximation in agreement with the doubling of the number of degrees of freedom per molecule (compared with atomic crystals).The polypeptide behavior is, however, different. The specific heat for each form exhibits a thermal dependence connected with a strong vibrational anisotropy. The model proposed earlier by Tarasov accounts well for these results. In the case of the β form, we have observed the predicted three- and two-dimensional behavior due to the intermolecular H bondings responsible for the sheet structure. For the α form we observed a one-dimensional pattern at higher temperature, since each peptidic chain vibrates separately.The comparison with other spectroscopic and theoretical investigations shows a large discrepancy. However, we have attemped to account for the “optical contribution” to the specific heat of poly(L-alanine) by using a continuum of mean frequencies as suggested by Wunderlich. Vibrational frequency spectra are proposed to explain our results, but the overlapping of acoustical and optical branches in the case of the α form outlines the limits of macroscopic models. It is quite likely that the acoustical spectrum is greatly affected by the intramolecular H bonding.At low temperature the specific heat is a physical property sensitive to the long-range order of the macromolecule, and therefore further spectroscopic and theoretical investigations are necessary to explain correctly these experimental results.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140410
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  • 114
    Electronic Resource
    Electronic Resource
    Conformational states of poly(L-tyrosine) in aqueous solution (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 849-869 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(L-tyrosine) [(L-Tyr)n] has been characterized in aqueous solution using circular dichroism (CD) and infrared (ir) spectroscopy, and ultracentrifugal analysis. Most of the experiments were carried out at 0.01% polymer or less to avoid the complications caused by precipitation previously encountered by others. This permitted us to study solutions of (L-Tyr)n at lower pH values than had been attained previously. Our results show that a transition to an antiparallel-β conformation occurs at pH 11.32 upon titration from higher pH. The β structure is intramolecular when first formed and aggregates with time or upon titration below pH 11. Ultracentrifugal analysis of the intramolecular β conformation shows that it is quite compact, with a frictional coefficient ratio, f/fmin, of 1.09. In addition to the β structure, a nonordered form of the polymer has been obtained below pH 11 by rapid titration of the ionized polyelectrolyte. This form is nonaggregated and was found to have an f/fmin of 1.01, and is therefore almost spherical. The aggregated β form was found to be thermodynamically more stable than the nonordered form at pH 10.7.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140413
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  • 115
    Electronic Resource
    Electronic Resource
    A new technique for optical observation of the kinetics of chemical reactions perturbed by small pressure changes (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 883-887 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140415
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  • 116
    Electronic Resource
    Electronic Resource
    An “acid” structure for polyriboguanylic acid observed by X-ray diffraction (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 889-890 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140416
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  • 117
    Electronic Resource
    Electronic Resource
    On the nonplanarity of the peptide groups in the ω-helix of polypeptides (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 891-893 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140417
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  • 118
    Electronic Resource
    Electronic Resource
    Conformation of histidine model peptides. II. Spectroscopic properties of the imidazole chromophoreTaken in part from a dissertation submitted by P. E. Grebow in partial fulfillment of the requirements for the Ph.D. degree, University of California, Santa Barbara, 1973. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 871-881 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Semi-empirical molecular orbital calculations have been carried out for the free base and cationic forms of imidazole so as to obtain data which are required for the calculation of the chiroptical properties of molecules that contain this chromophoric group. The polarization, energy, and monopolar charge distribution are reported for the lowest energy electronic transitions. The absorption spectra for imidazole have been determined to 180 nm and circular dichroism spectra for L-histidinol and L-2-amino-1-butanol have been measured.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140414
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  • 119
    Electronic Resource
    Electronic Resource
    Masthead (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140501
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  • 120
    Electronic Resource
    Electronic Resource
    Structure of the collagen microfibril. A four-strand overlap model (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 895-900 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140418
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  • 121
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    Studies on deoxyribonucleoprotein structure. Small-angle X-ray scattering in solutions of various ionic strengths (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1133-1142 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cross-sectional radius of gyration of the deoxyribonucleoprotein (DNP) threads was measured by small-angle X-ray scattering in a wide range of ionic strengths (from 0.0005 to 2 M NaCl). For DNP in a solution of low ionic strength, this value is 30 Å. The increase of ionic strength results in partial deproteinization of DNP, while the cross-sectional radius of gyration varies from 25 Å for DNP in 0.7 M NaCl to 10 Å for DNP in 2 M NaCl. It is suggested that gradual deproteinization by the increase of NaCl concentration causes conformational changes, which are associated with the alteration of the DNP superstructure. The data are interpreted on the basis of the superhelical model of DNA packing in DNP; however, the coexistence of superhelical and unfolded regions in the DNP structure is also a possibility.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140603
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    The buoyant and potentiometric titrations of human immuno-gamma globulin (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1161-1171 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The buoyant density and potentiometric hydrogen ion titration curves of human immuno-gamma globulin in 3M cesium chloride have been recorded. In addition, the amino acid analysis of the IgG employed has been completed. The hydration of the protein and the variation of the hydration with pH have been calculated from the buoyant density data. The potentiomtric hydrogen ion titration curve has been employed to estimate the intrinsic pK′s of the acidic and histidyl residues of the molecule, and to confirm the hypothesis that it does in fact conform to the oil drop model of protein conformation. Correlations have been drawn between the three sets of data in the following manner. The results of the potentiometric hydrogen ion titration have been checked against the amino acid analysis to determine whether the numbers of groups observed to titrate and the numbers of groups observed in the amino acid analysis do correspond. Second, previous hypotheses as to the direct correlation between potentiometric hydrogen ion titration behaviour and buoyant density titration behaviour have been investigated and substantially confirmed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140605
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  • 123
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    On the displacement of cooperative transitions of linear biopolymers by an electric field (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1173-1179 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A basic theory for equilibrium properties of cooperative transitions (particularly helix-coil transformations) of sufficiently long linear biopolymers under the influence of an electric field is developed. General relations for the calculation of the distribution of uninterrupted sequences of elementary subunit states (e.g., helical fragments) as well as the overall degree of transition θ are given. Strong cooperativity is found to permit simplifications. It is shown that only in this case can a practically significant field effect be expected. Numerical results are presented for a special example of experimental interest.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140606
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  • 124
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    Nmr study of the structure of short-chain peptides in solution (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1143-1160 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron-mediated spin-spin coupling constant J between the amide NH and the α-CH protons in the dipeptide fragment Cα—CO(NH—CαH)R—C′ONH—Cα is dependent on the dihedral angle of rotation (Φ) around the N—C bond. Measurement of J in a series of zwitterionic dipeptides H3N+—CHR1—CONH—CHR2—CO2- (which is conformationally similar to the dipeptide fragment) in TFA solution shows that J is independent of R1, but dependent on the steric bulk of R2. The data are interpreted in terms of a model that assumes that what we measure is an average value of J—a thermal average over all the possible rotamers. The groups R1 and R2 are, in most cases, sterically kept apart by the trans and planar amide bonds, and hence the independence of J of R1. This model is consistent with the theoretical calculations done on the dipeptide fragment. The effect of the structural characteristics of the side chains (e.g., the effect of lengthening and branching the side chains) on the J values in dipeptides is discussed in the light of the existing results of theoretical calculations.Study of 〈J〉 values in tripeptides (C6H5CH2OCONH—CHR1—CONH—CHR2—CO2CH3, essentially three linked peptide units) shows that electrostatic interaction between the two amide bonds modifies the potential energy surface and the 〈J〉 value of a dipeptide subunit in the tripeptides. Also in some cases, direct steric interaction between the two side chains in the two adjacent dipeptide subunits in the tripeptide affects the potential energy surfaces of the individual dipeptide subunits and hence the 〈J〉 values. The influence of the structural characteristics of the side chains of individual amino acids on structure formation at or beyond the dipeptide level is discussed at various points.The J(NH—αCH) values of CH3CONH—CHR—CONH2 and CH3CONH—CHR—CO2CH3 with the same R are quite different for R = valine, leucine, phenylalanine, methionine, but equal for R = glycine. This, coupled with the fact that one of the carboxamide NH resonances has a chemical shift different from its counterpart in simple amides like CH3CONH2 and the other carboxamide NH has the same chemical shift as its counterpart in CH3CONH2, suggest the presence of a hydrogen bond in dipeptide CH3CONH—CHR—CONH2 with carboxamide NH as the donor. Theoretical evidence for two seven-membered hydrogen-bonded rings with the carboxamide NH as donor and the acetyl oxygen as acceptor is summarized. Our data cannot suggest the number of such hydrogen-bonded rings, nor can they conclude the relative proportion of these rings in a particular dipeptide. A discussion of the difficulty of interpretation is presented and the data are discussed under certain simplifying assumptions.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140604
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  • 125
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    The effects of cooperativity, finite chain length, and field-induced changes of the conformational equilibrium on the electric birefringence of polypeptides in the range of the helix-coil transition (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1181-1195 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An electric birefringence apparatus with an He-Ne laser is described, which permits a high sensitivity of measurement for field strengths up to 20 kV/cm and pulse durations between 10-5 to 1 sec. It is applied to poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) in a nonaqueous solvent mixture, especially under the conditions of the helix-coil equilibrium. A theoretical treatment of the problem shows that the usual neglect of end effects is only justified for comparatively long chains. On the basis of a computational procedure taking into account the finite chain lengths, the experimental data for 15 kV/cm reveal an obvious enhancement of the coil-to-helix transition caused by the electric field. This effect is quantitatively confirmed by a pertinent theory. The cooperative parameter σ may be best determined from the initial linear increase of the bire-fringence versus the square of the field strength where the conformational equilibrium is not affected.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140607
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  • 126
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    Quantum-mechanical study of the hypochromic effect in polynucleotides. Intra- and interstrand interaction contributions (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1205-1212 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first uv absorption band hypochromism of poly(dA) · poly(dT), poly(dG) · poly(dC), poly(dA), poly(dT), poly(dG), and poly(dC) is calculated with the help of perturbation theory on the basis of monomer characteristics computed by the Pariser-Parr-Pople method taking into account all singly excited configurations. The theoretical results obtained are in good agreement with experimental values of hypochromism. The origin of the hypochromic effect in the double-stranded polynucleotides is investigated. It is shown that intrastrand interactions between the bases make the main contribution to hypochromism (60-76%), while the contribution of the Watson-Crick-pair formation is small (2-12%). The essential part of hypochromism (22-28%) is due to the interstrand interactions between the bases that are not coupled by hydrogen bonds. The discussion of the experimental data shows that the present theoretical investigation could serve as a basis for the correct treatment of experimental data.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140609
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  • 127
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    An X-ray diffraction study of poly-L-homoarginine hydrochloride (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1197-1204 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An X-ray study of the synthetic polypeptide poly(L-homoarginine hydrochloride) has been made to investigate whether, like the chemically related polypeptides poly(L-lysine hydrochloride), poly(L-arginine hydrochloride), and poly(L-ornithine hydrobromide), it can undergo conformational transitions merely from variations in its degree of hydration. X-ray photographs of powder and oriented specimens containing one to 15 molecules of water per L-homoarginine hydrochloride residue showed that this polymer forms only a β-pleated-sheet structure. The pleated sheets, formed by antiparallel polypeptide chains hydrogen-bonded to each other, are piled up along the b axis in an alternating sequence (“sandwich structure”). This structure did not appreciably change with variations of the degree of hydration, and the observed reflections at 56% relative humidity (1.8 molecules of water per residue) could be indexed satisfactorily in terms of a monoclinic unit cell, of space group P21, with a = 9.34 Å, b = 40.07 Å, c = 6.94 Å, and γ = 106°. These dimensions are shown by models to be compatible with the proposed structure, and the calculated density of 1.27 g/cm3 agrees well with the experimental value of 1.29 g/cm3. Removal of the last molecule of water results in a very diffuse pattern, while specimens containing 20 molecules of water per residue show only reflections due to water.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140608
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  • 128
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    Carbon-13 and proton nmr studies of helix-coil transition of poly(γ-benzyl-L-glutamate) (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1223-1230 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil conformational transition undergone by poly(γ-benzyl-L-glutamate) in solutions of trifluoroacetic acid and deuterated chloroform was studied by proton and carbon-13 nmr. The results indicate that in the case of the solvent-induced helix-coil transition, the side chain assumes a helical conformation before the backbone. In the thermally induced helix-coil transition, the results indicate the existence of an intermediate state, which is between the α-helix and random coil and is free from intramolecular hydrogen bonding.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140611
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  • 129
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    On the various types of circular dichroism induced on acridine orange bound to poly(S-carboxymethyl-L-cysteine) (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1213-1221 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism and absorption spectra are measured on mixed solutions of acridine orange and poly(S-carboxymethyl-L-cysteine) at different pH and P/D mixing ratios. The observed circular dichroism spectra are classified into several types, mainly based on the number and sign of circular dichroic bands in the visible region. Three of them are associated with the absorption spectra characteristic of dimeric dye or higher aggregates of dye. Type I is observed with solutions, of which the pH is acid and P/D is higher than 4, and it has an unsymmetrical pair of positive and negative dichroic bands at 470 and 430 nm. This type is induced on the dye bound to the polymer in the β-conformation. Types II and III are considered to be characteristic of randomly coiled polymers. Type II is exhibited by solutions of P/D higher than 1 at pH 5-7 and has two dichroic bands around the same wavelengths as Type I but with opposite signs and an additional positive band at 560 nm. Type III, shown by solutions of P/D 2-0.6 at pH 6-10.5, has three dichroic bands around the same wavelengths as Type II but with signs opposite to it. The other two types of circular dichroism, induced for the solutions of P/D less than 1 at slightly acid pH, are associated with the absorption spectra of monomeric dye and are observed with disordered or randomly coiled polymer. They have a pair of dichroic bands at 540 and 425 nm, and the signs of these bands are opposite to each other in these two types.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140610
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  • 130
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    Basic polypeptides as histone models. Synthesis, conformation, and interaction with DNA of statistical copolymers (Lysx,Alay)n (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1231-1244 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Statistical copolymers (Lysx,Alay)n were synthesized by copolymerization of N-carboxyanhydrides of L-amino acids. The conformation of copolymers in aqueous solutions was investigated using circular dichroism (CD). Calculations based on the CD data showed that polymers (Lysx,Alay)n can exhibit a random conformation, an α-helix, and a β-structure in various ratios. CD spectra of complexes of copolymers with DNA prepared by gradual dialysis from a high ionic strength to 0.15 M NaCl can be correlated with the copolymer conformation in medium and high ionic strength. For copolymers forming an α-helix and β-structure, these spectra show resemblance with similar spectra of complexes of those histones that are able to exhibit ordered conformations.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140612
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  • 131
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    Characterization of the A ⇄ B transition of DNA in fibers and gels by laser Raman spectroscopy (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1245-1257 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both Raman spectra and X-ray diffraction patterns have been obtained from oriented fibers of sodium deoxyribonucleic acid (Na-DNA) as a function of salt content and relative humidity. We have confirmed the previously reported X-ray results that, for oriented fibers, the A-form always exists between 75 and 92% relative humidity and that the conformation will change to the B-form at 92% relative humidity only if an excess (3-5%) of added salt is present. Oriented fibers containing low amounts of added salt remain in the A-type conformation at 92% relative humidity and higher. An exact correlation has been found between the familiar A- and B-type X-ray diffraction patterns of DNA fibers and the Raman spectra previously reported without X-ray verification from this laboratory for the A- and B-forms. In particular, a band at 807 cm-1 was always present when a fiber showed the A-type diffraction pattern, and this band shifts to 790 cm-1 in the B-form. Using the Raman spectrum to determine the specific conformation of DNA in samples less amenable to X-ray analysis, we have studied the A ⇄ Btransformation in unoriented fibrous masses of DNA and in concentrated, oriented gels. We find that in unoriented fibrous masses, the A ⇄ B transition always occurs at 92% relative humidity even at very low salt concentration (0-4%). However, in oriented DNA gels at low salt, the A-form can persist as a metastable state to concentration as low as 20% DNA. The origin of the bands at 807 and 790 cm-1 and the possible biological implications of these findings are discussed.
    Additional Material: 9 Ill.
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  • 132
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    Analysis of the effects of chloride and 2,3-diphosphoglycerate on the cooperative binding of oxygen to hemoglobin (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1273-1281 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of experimental equilibrium constants for the oxygenation of hemoglobin leads to a plausible mechanism for the effect of pH and of chloride ions on cooperativity in hemoglobin. According to this mechanism, the structural changes responsible for cooperativity in chloride- and 2,3-diphosphoglycerate-free hemoglobin are affected only slightly by changes in pH, and the effect of chloride can be accounted for by sequential binding and release of chloride ions during oxygenation.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140615
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  • 133
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    Conformational geometry and vibrational frequencies of nucleic acid chains (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1259-1271 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Normal coordinate analysis of diethyl phosphate has been made, which predicts all observed Raman frequencies in the range 170-1300 cm-1. The force constants from this calculation have been transferred to a vibrational calculation for a simplified model of the backbone of nucleic acids, which also involves the —O—PO2-—O phosphate group and the —C5′—C4′—C3′—linkage of the ribose. The coordinates of these atoms are those recently given by Arnott and Hukins, which place the ribose ring of B-DNA in a C3′-exo conformation. This simple polymer model appears to be able to describe adequately the frequency-dependent changes observed in the Raman spectra arising from the backbone vibrations of nucleic acid in going from the B- to A-form. The symmetric —O—P—O— diester stretch increases in frequency from about 787 cm-1 in the B-form to 807 cm-1 in the A-form. The increased frequency characteristic of the A-form is due to the combining of the diester stretch with vibrations involving the C5′, C4′, and C3′ nuclei. The frequency of the symmetric —O—P—O— diester stretch is shown to be very dependent on the conformation of the ribose ring, indicating that in polynucleotides the ribose ring takes on one of two rigid conformations: C3′-endo for A-form or C3′-exo for B-form and “disordered” polynucleotides. The calculation lends confirmation to the atomic coordinates of Arnott and Hukins since the use of other geometries with the same force constants failed to give results in agreement with experimental evidence. The calculations also demonstrate the lowering effect of hydration on the anionic PO stretching frequencies. Experimental results show that the 814-cm-1 band observed in the spectra of 5′GMP gel arises from a different vibrational mode than that of the 814-cm-1 band of A-DNA.
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    Levans. II. Light-scattering and sedimentation data of Streptococcus salivarius levan in water (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1283-1292 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular weights and radii of gyration of Streptococcus salivarius levan fractions were obtained from light-scattering measurements in water. Sedimentation coefficients and partial specific volumes of the fractions were also obtained. Double logarithmic plots of [η] versus M̄w and S0 versus M̄w yielded slopes having values of 0.17 and 0.62, respectively. The data and various calculated parameters show that levan from Streptococcus salivarius is highly branched and behaves hydrodynamically as a compact particle of spherical symmetry.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140616
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    Magnetic susceptibility of ferrihemoglobin in water and 5% t-butanolPublication 81 from the Laboratory for Biophysical Chemistry. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1293-1304 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molar magnetic susceptibility of ferrihemoglobin solutions, as a function of pH and temperature using the nmr technique of Evans, in water and 5% t-butanol has been determined. Results suggest that within a small pH region, the conventional analysis of magnetic susceptibility in terms of high-spin and low-spin contributions breaks down. The implication of this is discussed in terms of possible conformational change involving two subspecies. The effect of t-butanol is also discussed in terms of the t-butanol effect on water.
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    The ultraviolet transitions of the ethidium cation (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1309-1312 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140619
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    Insulinanaloga mit N-terminal verlängerter B-Kette100. Metteilung über Peptide; 99. Mitt. s. H. Berndt u. H. Zahn, Liebigs Ann. Chem., i. Druck.Prof. Dr. Herman Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 7-22 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: NαA1, NεB29 -Bis(tert-butyloxycarbonyl)insulin, easily obtained by selective butyloxycarbonylation of insulin according to Geiger, was purified by chromatography and applied as amino component for peptide syntheses with active esters of amino acids protected by the butyloxycarbonyl group. By this method the partial synthesis of NαB1-leucyl-, glycyl-, lysyl-, and glutamylinsulin was achieved. The analogues showing homogeneity in electrophoresis (pH 2 and 8,6) and thin layer chromatography, were characterized by biological, immunological, and CD-spectral data and could be crystallized.
    Notes: Das nach Geiger durch selektive Butyloxycarbonylierung von Insulin leicht zugängliche NαA1, NεB29 -Bis(tert-butyloxycarbonyl)insulin wurde chromatographisch gereinigt und als Aminokomponente für Peptidsynthesen mit aktiven Estern von tert-Butyloxycarbonyl-geschützten Aminosäuren eingesetzt. Auf diese Weise gelang die Partialsynthese von NαB1- Leucyl-, Glycyl-, Lysyl- und Glutamylinsulin. Die elektrophorestich (pH 2 und 8,6) und dünnschichtromatographisch einheitlichen Analoga wurden durch biologischet, immunologische und CD-spektrale Daten charakterisiert und konnten kristallisiert werden.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975102
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    Polymere ester von säuren des Phosphors, 31. und 2. Mitt.: Makromolekulare Chem. 163 (1973) 89 und 111.. Polymerisation des 2-Äthoxy-2-oxo-1,3,2-dioxaphospholansProf. Der. Herman F. Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 97-110 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Ethoxy-2-oxo-1,3,2-dioxaphospholane (1) is polymerized rapidly and in high yields to poly[oxy(ethoxyphoxyphosphoryl)oxyethylene] (3) by several alcoholates. The products are colourless and of high viscosity. They are soluble in water, alcohols, tetrahydrofuran, dioxane, methylene, chloride, chloroform, and dimethylsulfoxid; they are insoluble in ether and in hydrocarbons. Polymerization degrees up to 83 (M̄ = 12600) were found. In aqueous solutions no hydrolytic degradation is observed at room temperature within several days.A tentative anionic mechanism of polymerization and possible side reactions are briefly discussed.
    Notes: 2-Äthoxy-2-oxo-1,3,2-dioxaphospholan (1) wird durch verschiedene Alkoholate sehr schnell und in hoher Ausbeute zu Poly[oxy(äthoxyphosphoryl)oxyäthylen] (3) polymerisiert. Die Produkte sind hochviskos und farbols. Sie lösen sich in Wasser, Alkoholen, Tetrahydrofuran, Dioxan, Methylenchlorid, Chloroform und Dimethylsulfoxid; unlöslich sind sie in Äther und in Kohlenwasserstoffen. Polymerisationsgrade bis 83 (M̄ = 12600) wurden gemessen. In wäßriger Lösung bei Raumtemperatur erfolgte auch nach Tagen kein merklicher hydrolytischer Abbau.Der mutmaßlich anionische Polymerisationsmechanismus und mögliche Nebenreaktionen werden kurz diskutiert.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975106
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    The propagating species in the polymerisation of 1,3-Dioxacycloalkanes by Perchloric AcidDedicated to Herman Mark (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 203-216 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Zweck der vorliegenden Arbeit war, eine Entscheidung zwischen den «Mainz»- und «Keele-Theorien» über die Polymerisation der 1,3-Dioxacycloalkane durch wasserfreie Perchlorsäure in Methylendichlorid herbeizuführen. Mittels der Jaacks'schen Methode zur Bestimmung von tertiären Oxoniumionen entdeckten wir, daß deren Konzentration verschwindend klein ist, wenn unter peinlichstem Ausschluß von Feuchtigkeit polymerisiert wird. Wir erzielten diese Resultate mit 1,3-Dioxolan (1), 4-Methyl-1,3-dioxolan (4) und 1.3-Dioxepan (5). Sie wurden durch unsere Bestimmungen des Gehaltes an Hydroxy-Gruppen unterstützt, die an Polymeren vorgenomrnen wurden, welche mit verschiedenen Redgenzien neutralisiert worden waren.Es folgt hieraus. dall bei eincm Wassergehalt der Reaktionsgemische von weniger als ca. 10-4M die Fortpflanzung überwiegend durch sekundäre Oxoniumionen stattfindet. so daß sie nach dem Plesch-Westerrmann'schen Ringerweiterungsmechanismus verlaufen muß. Da Wasser die Bildung von tertiären Oxoniumionen verursacht. läßt es sich erklären, wieso andere Forscher und auch wir, zuvor in weniger sorgfältig durchgeführten Ansätzen, diese Ionen (manchmal sogar in überwiegenden Mengen) nachweisen konnten.Unsere Befunde beinhalten auch. daß Penczeks Theorie, welche coordinierte Oxy-Carbe-niumionen als die wachsenden Zentren betrachtet, auf die hier diskutierten Systeme nicht anwendbar ist.Der heuristische Wert der Kingerweiterungstheorie wird hier kurz durch einen Hinweis auf eine daraus entstandene neue Methode zur Synthese von «Kronen-Athern» aus 1,3-Dioxacykloalkanen veranschaulicht.
    Notes: The object of the work described was to discriminate between the two principal rival theories concerning the polymerisation of 1,3-dioxacycloalkanes by anhydrous perchloric acid, the “Mainz theory” and the “Keele theory”. By means of Jaacks's method for determining tertiary oxonium ions we found that in polymerisations under the driest conditions the concentration of these is negligibly small. This was done with 1,3-dioxolane (1), 4-methyl-1,3-dioxolane (4), and 1,3-dioxepane (5), and the findings are supported by determinations of the content of hydroxy groups of polymers prepared and “killed” under different conditions.It follows that when the water content of the reaction mixtures is less than ca. 10-4M the propagation is principally by secondary oxonium ions, and that it must therefore go by the ring-expansion mechanism of Plesch and Westermann.Water causes the formation of tertiary oxonium ions and this probably explains why previously other workers and ourselves had reported their presence, and sometimes their dominance, in reaction mixtures prepared under much less stringent conditions.The recent theory of Penczek, which involves co-ordinated oxy-carbenium ions, is also shown not to be applicable to the systems considered here. -  The heuristic value of the ring-expansion theory is illustrated briefly by reference to a new method of synthesising crown ethers from 1,3-dioxacycloalkanes, which arose from it.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975113
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    Polymer induced aggregation of dye moleculesDedicated to Professor Herman Mark at the occasion of his 80th birthday anniversary (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 249-261 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß verschiedener Polysäuren auf die Absorptionsspektren von 7-Methylamino-3-dimethyliminio-3H-phenothiazinchlorid (Trimethylthioninhydrochlorid, Azur B) (1) wurde untersucht. Folgende Polymere wurden eingesetzt: Polyacrylsäure, verschiedene Acrylsäure-Acrylamid- und Acrylsäure-Styrol-Copolymere sowie drei Maleinsäure-Acrylamid-Copolymere. Die spektroskopischen Messungen der Farbstoff-Polymer-Wechselwirkungen zeigten, daß die Farbstoffmoleküle mit der Polymerkette assoziiert sind und daß diese Assoziationen stark abhängig sind von der Copolymeren-Zusammensetzung, vom Abstand zwischen den Carboxylgruppen in der Kette und von der inneren Struktur der Makromoleküle. Bei gleichem Acrylsäuregehalt in verschiedenen Styrol-Acrylsäure-Copolymeren beeinflußt auch die Triadensequenzverteilung die Intensität der metachromatischen Banden, obwohl dieser Einfluß nur von untergeordneter Bedeutung ist, verglichen mit den anderen strukturellen Merkmalen der Copolymeren.
    Notes: The effect of various polyacids on the absorption spectrum of 7-methylamino-3-dimethylimino-3H-phenothiazine chloride (trimethylthionine chloride, Azure B) (1) was studied. The following polymers were used: poly(acrylic acid), several acrylic acid-acrylamide and acrylic acid-styrene copolymers, and three maleic acid-acrylamide copolymers. The spectroscopic measurements of the dye-polymer interactions showed that the dye molecules are associated with the polymer chain and that this association is strongly dependent on the copolymer composition, the distance between the carboxylic groups in the chain, and the internal structure of the macromolecule. At identical acrylic acid content of poly(styrene-co-acrylic acid), the triads sequence distributions affect also the intensity of the metachromatic band, though this influence is only of secondary importance compared to the other structural characteristics of the copolymers.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975117
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  • 141
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    On the melting behaviour of isotactic polymers obtained from optically active and racemic 4-methyl-1-hexeneDedicated to Professor Dr. H. Mark on his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 317-327 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das thermische Verhalten von isotaktischem Poly[(S)-4-methyl-1-hexen], (P(S)4MH), Poly[(R)-4-methyl-1-hexen], (P(R)4MH), ihrer àquimolaren Mischung (r-P4MH) und von Poly[(R)(S)-4-methyl-1-hexen] (P4MH) wurde untersucht. Die DSC-Kurven von P(S)4MH und P(R)4MH ergaben beim Schmelzen zwei endotherme Peaks, während nur ein Peak in den DSC-Kurven von r-P4MH und P4MH gefunden wurde.Für die optisch aktiven Polymeren wird die Bildung einer Mesophase vorgeschlagen und die experimentellen Ergebnisse werden auf der Basis der Konformation dieser Polymeren im kristallinen und flüssigen Zustand besprochen.
    Notes: The thermal behaviour of isotactic poly[(S)-4-methyl-1-hexene], (P(S)4 MH), isotactic poly[(R)-4-methyl-1-hexene], (P(R)4 MH), of their equimolar mixture (r-P4MH) and of poly[(R)(S)-4-methyl-1-hexene], (P4MH), was investigated. The DSC curves obtained by melting P(S)4MH and P(R)4MH showed two endothermic peaks, while only one peak was found in the DSC curves obtained by melting r-P4MH or P4MH.For the optically active polymers the formation of a mesophase is proposed and the results are discussed on the basis of the conformation of these polymers in the crystalline and in the liquid state.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975122
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  • 142
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    Zur Konzentrationsabhängigkeit der Viskosität in verdünnten Lösungen von (technischen) PolyisobutylenenHerrn Prof. Dr. H. Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 387-400 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The dependence of the Huggins constant kH on the intrinsic viscosity [η], the coil expansion factor α, and the molecular weight was investigated by measuring highly diluted solutions of polyisobutylene. After extrapolation to zero shear rate, the kH-values were derived by using the best suiting Martin-equation. The resulting relations between kH and [η] (resp.α) were compared with theoretical and semiempirical formulas published by Moore-Bodhanecky, Imai, and Sakai. With weakly expanded systems, we found fair agreement with the Sakai-function. From this, it may be concluded that the Sakai-function describes adequately the determining factor of coil penetrability. In strongly expanded systems, kH decreases with [η]-1 and α-3, resp. An attempt is made to explain the results in terms of structural rheology.
    Notes: Anhand von Messungen an Lösungen von Polyisobutylen wurde die Abhängigkeit der Huggins-Konstanten kH vom Staudinger-Index [η], von der Knäuelaufweitung α und vom Molekulargewicht untersucht. Die kH- Werte wurden nach der Extrapolation der Meßwerte auf verschwindende Scherrate nach der Martin-Gleichung gewonnen, die sich als am besten geeignet zur Linearisierung von ηred erwies. Die gefundenen Beziehungen zwischen kH und [η] bzw. α wurden mit theoretischen bzw. halbempirischen Formeln von Moore-Bodhanecky, Imai und Sakai verglichen. Bei nicht sehr stark aufgeweiteten Systemen wurde gute Übereinstimmung mit der Sakai-Beziehung erzielt, woraus geschlossen wird, daß diese Funktion die Wirkung der Knäueldurchdringung richtig beschreibt. In stärker aufgeweiteten Systemen fällt kH mit [η]-1 bzw. α-3 ab. Es wird versucht, diese Ergebnisse strukturrheologisch zu interpretieren.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975126
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    Liquid-liquid phase separation in multicomponent polymer systems, 12Part 11 cf.23.. Molecular weight dependence of the pair-interaction parameter in the system polystyrene/cyclohexaneDedicated to Professor Hermann F. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 401-414 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Messungen der thermodynamischen Stabilitätsgrenze (Spinodale) und des kritischen Zustandes im System Polystyrol/Cyclohexan mittels der “Pulse-Induced Critical Scattering” -und der Phasenvolumenverhältnis-Methode wurden übereinstimmende Werte erhalten, die darauf hinweisen, daß der Paar-Wechselwirkungsparameter im untersuchten System nicht allein von der Temperatur und der Gesamtpolymerkonzentration abhängen kann. Mit den erwähnten Meßmethoden kann man die zweite und die dritte Ableitung der freien Mischungssenthalpie nach der Konzentration ermitteln. Das beobachtete Verhalten kann mit einer ziemlich willkürlichen Funktion beschrieben werden, durch welche die Molekulargewichtsabhängigkeit des Wechselwirkungsparameters berücksichtigt wird. Es werden Gründe angeführt, warum man gewöhnlich findet,daß graphische Auftragungen nach Shultz-Flory linear sind, obwohl die zugrunde liegenden Annahmen selten oder nie gerechtfertigt sind.
    Notes: Consistent data have been obtained from measurements of the thermodynamic stability limit (spinodal locus) and of the critical point in the system polystyrene/cyclohexane by Pulse-Induced Critical Scattering and phase-volume-ratio techniques which involve direct measurement of the second and third derivatives of the free enthalpy (Gibbs free energy) of mixing with respect to concentration. These data indicate that the pair-interaction parameter in the system polystyrene/cyclohexane cannot depend on temperature and overall polymer concentration alone. The observed pattern can be described with a rather arbitrary empirical function for the molecular weight dependence of the interaction parameter. Arguments are advanced suggesting why Schultz-Flory plots are usually found to be linear, although the underlying assumptions are seldom, if ever, fulfilled.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975127
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    Some aspects of polymer hydrodynamicsDedicated to Professor Dr. H. Mark on his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 445-452 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die hydrodynamischen Gleichungen für ein Polymermolekül in einem gleichförmigen Geschwindigkeitsgefälle werden unter Benutzung der Modelle für kontinuierliche und in Segmente zerlegte Ketten aufgestellt. Die resultierenden Gleichungen sind ähnlich für beide Molekültypen, jedoch werden geringe Unterschiede, welche durch die örtliche Oberflächengeometrie der Polymerkette bedingt sind, gefunden. Die Resultate werden mit ähnlichen Berechnungen von Fujita verglichen. Es gibt einige Unterschiede im Detail, die aber ihrer Bedeutung nach vernachlässigt werden können.
    Notes: The hydrodynamic equations for a polymer molecule in a uniform velocity field are treated using models of continuous and segmented chains. The equations obtained are very much the same for both molecular types, but small differences are found depending on local surface geometry of the polymer chain. The results, are compared with a similar calculation of Fujita. There are some differences in detail, but these differences are of negligible significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975130
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  • 145
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    Beziehungen zwischen Molekularbewegung und Kettenstruktur in Styrol/Butadien-Copolymeren durch Messungen der 13C-Spin-Gitter-RelaxationHerrn Prof. Dr. H. Mark zum 80. Geburtstag mit den besten Wünschen gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 485-490 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: By measurements of the 13C spin lattice relaxation times (T1) of single 13C nuclei in solutions of random and blocklike styrene/butadiene-copolymers, polystyrene, and polybutadiene, it is shown that the segmental motion is influenced by the sequence distribution. The T1-values of 1,4-butadiene monomeric units at boundaries with styrene or with 1,2-butadiene units are different from the T1-values of 1,4-butadiene units in block sequences. Local conformational changes dependent on the structure of succeeding monomeric units must, therefore, contribute to the 13C spin lattice relaxation. In the styrene/butadiene-copolymers, the relaxation of the ortho-phenyl C-atoms is slower than the para-phenyl relaxation. This is interpreted by a rotational motion of the phenyl ring about the C-phenyl bond connecting it to the chain backbone. This rotational motion is about four times slower than the segmental motion.
    Notes: Durch Messung der 13C-Spin-Gitter-Relaxationszeiten (T1) einzelner 13C-Kerne in Lösungen von statistischen und blockartigen Styrol/Butadien-Copolymeren, Polystyrol und Polybutadien zeigt sich, daß die Segmentbewegung durch die Sequenzlängenverteilung beeinflußt wird. Die T1-Werte der 1,4-Butadienstruktureinheiten an Nahtstellen mit Styrolbzw. 1,2-Butadieneinheiten unterscheiden sich von den T1-Werten der 1,4-Butadieneinheiten in Blocksequenzen. Zur 13C-Spin-Gitter-Relaxation tragen daher lokale, von der Struktur aufeinanderfolgender Monomerbausteine abhängige Konformationsänderungen bei. In den Styrol/Butadien-Copolymeren erfolgt die Relaxation der ortho-Phenyl-C-Atome langsamer als die para-Phenyl-Relaxation. Die wird gedeutet durch eine Rotationsbewegung der Phenylringe um die Achse, die durch die Bindung zwischen Phenyl und Kette gegeben ist. Die Rotation verläuft etwa viermal langsamer als die Segmentbewegung.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975133
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    Reaktionen mit Silylaziden, 76. Mitt. cf.1.. Über 4-Isocyanatocarbonsäure-trimethylsilylester und 4-Aminocarbonsäure-N-carbonsäureanhydride (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 57-79 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Trimethylsilylesters of various 4-isocyanatocarboxylic acids (6a-h, 13, 14, 16, 17) were prepared by the reaction of cyclic 1,3-dicarboxylic acid anhydrides (10, 11, 12, 15) with trimethylsilyl azide (9). Mild hydrolysis of these silylesters yields 4-isocyanatocarboxylic acids, which in every case undergo addition polymerization to give unstable oligo(4-aminocarboxylic acid N-carboxylic anhydrides). Simultaneously cyclisation to crystalline, seven membered 4-aminocarboxylic acid-NCA (20 - 25) occurs. These cyclic NCA, however, cannot be observed or isolated in the case of all 4-isocyanatocarboxylic acids. Heat or basic catalysis induces decarboxylation of both linear and cyclic NCA with the formation of oligoamides (36, 37). Simultaneously, ring contraction occurs to give five membered lactams (26-30), which are the main products of thermal decarboxy-lation. In no case high molecular weight polyamides were obtained.
    Notes: Durch Umsetzung cyclischer 1,3-Dicarbonsäureanhydride (10, 11, 12, 15) mit Trimethylsilylazid (9) wurden verschiedene 4-Isocyanatocarbonsäure-trimethylsilylester (6a-h, 13, 14, 16, 17) erhalten. Durch schonende Hydrolyse dieser Silylester ließen sich die entsprechenden 4-Isocyanatocarbonsäuren freisetzen, die in allen Fällen der Additionspolymerisation zu den unbeständigen, linearen Oligo(4-Aminocarbonsäure-N-carbonsäureanhydriden) unterliegen. Parallel dazu erfolgt in manchen Fällen Cyclisierung zu kristallinen, siebengliedrigen 4-Aminocarbonsäure-NCA (20 - 25), die aber nicht von allen 4-Isocyanatocarbonsäuren beobachtet oder isoliert werden konnten. Beim Erhitzen sowie unter basischer Katalyse decarboxylieren sowohl die linearen als auch die cyclischen NCA unter Bildung von Oligoamiden (36, 37); parallel dazu erfolgt auch Ringverengung zu den entsprechenden fünfgliedrigen Lactamen (26-30), die insbesondere bei der thermischen Decarboxylierung die Hauptprodukte sind. Hochmolekulare Polyamide wurden in keinem Fall erhalten.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760106
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    Kinetics of 1,3,5-trioxacycloheptane formation in the electro-initiated copolymerization of 1,3-dioxolane with trioxane (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 143-156 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kinetik der Bildung von 1,3,5-Trioxacycloheptan (1,3,5-Trioxepan) bei der elektroinitiierten Copolymerisation von 1,3-Dioxolan mit Trioxan wurde untersucht. 1,2-Dichloräthan wurde als Lösungsmittel und Tetrabutylammoniumperchlorat als Leitsalz verwendet.Es wurde gefunden, daß bei Temperaturen zwischen 50 und 70°C 1,3,5-Trioxepan solange das Hauptprodukt der Wechselwirkung zwischen 1,3-Dioxolan und Trioxan ist, bis es eine Gleichgewichtskonzentration in diesem System erreicht, und daß 1,3,5-Trioxepan danach selbst an der Copolymerisation teilnehmen kann, unter Einbeziehung von 1,3-Dioxolan und TrioxanTemperaturabfall und Anstieg der Trioxankonzentration wirken sich ungünstig auf die Bildung von 1,3,5-Trioxepan aus, im Hinblick auf den Copolymerisationsprozeß. Sie scheint jedoch vom Lösungsmittel und der Natur des Katalysators weitgehend unabhängig zu sein.
    Notes: The kinetics of 1,3,5-trioxacycloheptane (1,3,5-trioxepane) formation in the electroinitiated copolymerization of 1,3-dioxolane with trioxane was investigated, using 1,2-dichloroethane as solvent and tetrabutylammonium perchlorate as background electrolyte. It was found that at temperatures between 50 and 70°C 1,3,5-trioxepane is the main product of 1,3-dioxolane/trioxane interaction till it reaches an equilibrium concentration in the system and that afterwards 1,3,5-trioxepane can take part itself in the copolymerization which involves 1,3-dioxolane and trioxane.1,3,5-Trioxepane formation with respect to the copolymerization process, was unfavoured by decreasing temperature and increasing trioxane concentration, whereas it seemed largely independent from solvent and catalyst nature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760110
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  • 148
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    1H-NMR spectrum of a model compound of stereoregular poly(methyl methacrylate) and poly(methacrylic acid) (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 225-228 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760117
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  • 149
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    ESCA spectra of fluorine containing polymers and their relation to the degree of crystallinity, to the surface tension and to the content of adsorbed gas (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 213-223 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: ESCA-Spektren von Poly(vinyliden fluorid), Poly(tetrafluoräthy1en) und Copolymeren von Tetrafluoräthylen und Äthylen wurden beobachtet. Dabei wurde festgestellt, daβ CK-Peaks in Dubletts aufgespalten werden, die —CF2— Einheiten in kristallinen Bereichen, den Windungen von —CF2— Einheiten im amorphen Bereich und —CH2—Einheiten im gesamten Polymer zugeordnet wurden. Der Kristallisationsgrad wurde anhand dieser Zuordnung abgeschätzt und mit den Ergebnissen der Röntgenstrahlbeugung verglichen. Die chemischen Verschiebungen der CK-Peaks wurden qualitativ mit der kritischen Oberflächenspannung verglichen. OK-Peaks wurden ebenfalls beobachtet und ihre relativen Intensitäten zum Gehalt an adsorbierten Gasen, wie z. B. O2, H2O und anderen, in Beziehung gesetzt.
    Notes: ESCA spectra of poly(vinylidene fluoride), polytetrafluoroethylene and copolymers of tetrafluoroethylene and ethylene were observed. CK peaks of them were split into doublets, which were assigned to —CF2— units in crystalline regions and the convolution of —CF2— units in amorphous regions and —CH2— units in the polymers as a whole. The degree of crystallinity was estimated according to the above assignment and compared with that from diffraction patterns. The chemical shifts of CK peaks were qualitatively compared with the critical surface tension. OK peaks were also observed in the polymers examined, and the relative intensities of them could be correlated with the content of absorbed gas such as O2, H2O, and others.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760116
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  • 150
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    Polymerization of cis- and trans-7,9-dioxabicyclo [4.3.0] nonane (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 299-313 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von cis- und trans-7,9-Dioxabicyclo[4.3.0]nonan (1a) und (1b) in Substanz und in Lösung wurde unter Verwendung von Phosphorpentafluorid und Triäthyloxoniumhexachlorantimonat als Initiatoren untersucht. Das cis-Isomere 1a bildet in hoher Ausbeute das cyclische Dimere 2a. Das trans-Isomere 1b polymerisiert under den gleichen Bedingungen leicht zu Polymeren mit niedrigen Molekulargewichten, wohingegen in 1,1,2,2-Tetrachloräthan-Lösung überwiegend das cyclische Dimere 2bentsteht. Die Polymerisation des trans-Isomeren 1b in Toluol-d8 Lösung verläuft nach erster Ordnung bezüglich des Monomeren wobei die Konzentration der aktiven Zentren während des Reaktionsablaufes unverändert zu bleiben scheint. Die Polymerisation von 1b in Toluol-d8 Lösung mit Phosphorpentafluorid als Initiator ist völlig reversibel bei Änderung der Temperatur. Die Standard Ceiling-Temperatur Tc0 dieser Polymerisation (Konz.: 1 mol/dm3 in Toluol-d8) liegt bei 118°C. Das cyclische Dimere 2b polymerisiert bei -25°C unter Gleichgewichtsbedingungen zu derselben Produktzusammensetzung wie das entsprechende Monomere 1b.
    Notes: The polymerization of cis- and trans-7,9-dioxabicyclo[4.3.0]nonane (1a) and (1b) was investigated in bulk and in solution with phosphorus pentafluoride and triethyloxonium hexachloroantimonate as initiators. The cis-isomer 1a forms in high yield the cyclic dimer 2a. The trans-isomer 1b polymerizes readily under similar conditions to relatively low molecular weight polymers, whereas in 1,1,2,2-tetrachloroethane solution predominantly the cyclic dimer 2b is formed. The polymerization of the trans-isomer 1b in toluene-d8 solution is of first order with respect to monomer, and the concentration of active species appears to remain constant throughout the reaction. The polymerization of 1b in toluene-d8 with PF5 as initiator is completely reversible with temperature change, and the standard ceiling temperature Tc0 is 118°C (cone.: 1 mol/dm3 in toluene-d8). The cyclic dimer 2b polymerizes at -25°C to the same equilibrium product composition as the corresponding monomer 1b.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760205
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    Synthese, Charakterisierung und Halbleitereigenschaften eines polymeren Indopheninhomologen (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 333-340 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Condensation of 2,3,7,8-tetraoxo-2,3,7,8-tetrahydropyrrolo[2′,3′:1,2]naphtho[5,6-b]-pyrrol (4) with thiopene yields a polymeric indophenine homologue (2), which is a vat dye. 2 has a coplanar conjugated π-electron system and the typical properties of a polymeric organic semiconductor of the p-type with a specific electrical conductivity of σ298K=1,8.10-5 Ω-1 cm-1 and a thermal activation energy of E=0,34eV(≈0,54.10-19J) at a pressure of p=1500kp cm-2 (14700 N cm-2). 2 has a specific concentration of unpaired spins of 5,6.1019 spins g-1.
    Notes: Durch Kondensation von 2,3,7,8-Tetraoxo-2,3,7,8-tetrahydropyrrolo[2′,3′:1,2]naphtho[5,6-b] pyrrol (4) mit Thiophen entsteht ein polymeres Indopheninhomologes (2). 2 ist ein Küpenfarbstoff und besitzt auf Grund seines koplanaren konjugierten π-Elektronensystems ausgeprägte Eigenschaften eines polymeren organischen Halbleiters. Es ist ein p-Leiter mit einer spezifischen elektrischen Leitfähigkeit von σ298k=1,8.10-5 Ω-1 cm-1 bei einer thermischen Aktivierungsenergie von E=0,34eV (≈0,54.10-19J), bei einem Druck von p=1500kp cm-2 (14700 N cm-2). 2 besitzt eine spezifische Spinkonzentration von 5.6.1019 spins g-1.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760207
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  • 152
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    Polymérisation et copolymérisation de l'acétoxy-1 butadièneNote préliminaire: G. Levesque et J.-C. Gressier, C. R. Acad. Sci. Ser. C, 277, 555 (1973). (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 341-350 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 1-Acetoxybutadiene (1a, b) can be polymerized under radical conditions as well in bulk, in benzene solution or in an aqueous emulsion. Polymers consist of ca. 80% 1, 4-units (4) and 20% 3,4-units (5), as determined by use of model compounds (2 and 3). Important chain transfer reactions to monomer, which have been measured, account for low number-average molecular weights (M̄n ≈ 5000).Radical copolymerisations with acrylic, vinyl, and diene monomers indicate 1a, b to be quite similar to isoprene in these reactions. Copolymers with M̄n ≈ 20 000 are readily obtained.1-Acetoxybutadiene polymers prepared via cationic catalysts are unstable unless careful purified. Anionic reagents are destroyed by this monomer even at -80°C.
    Notes: L'acétoxy-1 butadiène (1a, b) est polymérisé par les amorceurs radicalaires aussi bien en masse, en solution benzénique ou en émulsion aqueuse. Les polyméres formés renferment 80% de motifs -1,4 (4) et 20% de motifs -3,4 (5) ainsi qu'il ressort de l'étude de modèles (2 et 3) de ces structures. L'importance des réactions de transfert de chaǐne au monomère a été mesurée et rend compte de la valeur faible des masses molaires moyennes (M̄n ≈ 5000).La copolymérisation radicalaire a été étudiée avec des composés acryliques, vinyliques et diéniques: 1a, b présente une réactivité trés proche de celle de l'isoprène. Les copolymères ont couramment des M̄n de l'ordre de 20 000.Les polymères préparés par amorçage cationique sont instables à moins d'ětre soigneusement purifiés; enfin les amorceurs anioniques sont détruits dès -80°C par ce monomère.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.021760208
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    Kinetic study of the quaternization of tertiary amine as functional group in the poly(vinylpyridine) series with alkyl bromide (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 315-331 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktionsfähigkeit der funktionellen tert-Amin-Gruppen wurde durch Quaternierung von Homopolymeren und Copolymeren des 2-Vinyl-, 4-Vinyl- und 2-Me-thyl-5-vinylpyridins mit Butylbromid untersucht. Zum Vergleich wurde die Reaktionsfähigkeit von Modellsubstanzen herangezogen, wobei in allen Fällen eine Kinetikzweiter Ordnung während der ganzen Reaktion festgestellt wurde. Bei einem statistischen Styrol/Vinylpyridin-Copolymer mit geringem Gehalt an Pyridyläthylen-Grundbausteinen findet man für die Quaternierungskinetik ebenfalls zweite Ordnung, mit Ausnahme beim Styrol/2-Vinylpyridin-Copolymer, in dem die sterische Hinderung der entscheidende Faktor ist. Bei den Homopolymeren, im Falle des Poly(1-pyrid-4-yläthylens) [Poly(4-vinyl-pyridins)] bleibt es bei einer Kinetik zweiter Ordnung, bis die beiden Nachbargruppen einer gegebenen Reaktionsstelle quaterniert sind. Im Falle des Poly[1-(6-methyl-3-pyridyl)-äthylens] [Poly(2-methyl-5-vinylpyridins)] ist die Kinetik zweiter Ordnung nur solange eingehalten, bis eine Nachbargruppe einer gegebenen Reaktionsstelle quaterniert ist. Für Poly(1-pyrid-2-yläthylen) [Poly(2-vinylpyridin)] hängt die Kinetik allein von dem Ausmaß der sterischen Hinderung ab.Die Ergebnisse konnten an Hand von drei verschiedenen Geschwindigkeitskonstanten gedeutet werden, welche graphisch bestimmt werden können.
    Notes: The reactivity of tert-amine groups was studied by quaternization of homopolymers and copolymers of 2-vinyl-, 2-methyl-5-vinyl- and 4-vinyl-pyridine with butyl bromide. The reactivity of the corresponding model compounds was taken as a reference: in this case second order kinetics is obeyed until complete reaction of the pyridine derivatives. If the pyridylethylene repeating unit is included in a statistical styrene/vinylpyridine copolymer (with a low content of pyridylethylene units), the kinetics are of second order too, except for the styrene/2-vinylpyridine copolymer. In this case the steric hindrance due to the position of the nitrogen atom is the preponderant factor. For homopolymers, in the case of the quaternization of poly(1-pyrid-4-ylethylene) [poly(4-vinylpyridine)] second order kinetics are observed, until the adjacent reactive groups are quaternized. In the case of poly[1-(6-methyl-3-pyridyl)ethylene] [poly(2-methyl-5-vinylpyridine)] a second order law is obeyed only until one of the ajacent groups is quaternized.For poly(1-pyrid-2-ylethylene) [poly(2-vinylpyridine)] steric hindrance effects govern strictly the behaviour of the functional group.These results were interpreted by introducing three individual velocity constants which were determined graphically.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.021760206
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  • 154
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    A new method for the synthesis of polymers containing amide and imide groups in the main chain (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 351-363 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Pyromellitsäuredianhydrid (6) und Dicarbamaten (5) (Diurethanen), die Amidbindungen enthalten, wurden Poly(pyromellitdiimidoarylencarbonyliminoaryleniminocarbonylarylen)e [Poly(amid-imid)e] (7 und 12) hergestellt. Dieselben Polymeren konnten auch direkt aus aromatischen Isocyanatocarbonsäurechloriden (10), Diaminen (11) und 6 hergestellt werden. Im letzteren Fall was eine äquimolare Menge Wasser für die Bildung des Imidringes in der Polymerhauptkette erforderlich. Durch Modellreaktionen wurden die Reaktionsbedingungen für beide Methoden bestimmt und Reaktionsmechanismen vorgeschlagen.
    Notes: Poly(pyromellitdiimidoarylenecarbonyliminoaryleneiminocarbonylarylene)s [poly(amide-imide)s] (7 and 12) were prepared from pyromellitic dianhydride (6) and dicarbamates (5) (diurethanes) containing amide linkages. The same polymers could also be prepared directly from aromatic isocyanatocarboxylic acid chlorides (10), diamines (11) and 6. In the latter method, the addition of an equimolar amount of water was required for the formation of the imide ring in the main chain of the polymer. Model reactions were carried out to determine the reaction conditions for the two methods. Reaction mechanisms are proposed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760209
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    Lösungseigenschaften von Copolymeren des Acrylnitrils in N,N-DimethylformamidHerrn Prof. Dr. H. Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 367-386 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The critical precipitant concentrations in the system poly(acrylonitrile-co-methyl acrylate)/N,N-dimethylformamide/acrylonitrile were determined by viscometry. Above the critical precipitant concentration gel is formed: the viscosity becomes time dependent. Thegel formation tendency increases with increasing molecular weight of the acrylonitrile/methyl acrylate copolymers. The gel formation tendency decreases with increasing content of copolymerized methyl acrylate.Light scattering and viscosity measurements of dilute solutions of acrylonitrile/methyl acrylate copolymers with 5,8 wt.-% methyl acrylate were conducted. The molecular weight versus intrinsic viscosity relation is given by: \documentclass{article}\pagestyle{empty}\begin{document}$$ [\eta ] = 1,15 \cdot 10^{-2} M_w^{0,83} $$\end{document} The dependence of the weight average mean square radius of gyration on the molecular weight is given by the equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \left\langle {r_w^2 } \right\rangle = 3,15 \cdot 10{\rm }^{{\rm 18}} M_w^{1.185} $$\end{document} The results are compared with data for polyacrylonitrile. which were reported by Fujisaki and Kobayashi.Unperturbed dimensions were calculated from the molecular weight dependences of the radius of gyration and the intrinsic viscosity. From the unperturbed dimensions the persistence length and the statistical chain element according to Kuhn were computed. Insertion of methyl acrylate in acrylonitrile copolymers increases the chain flexibility. The persistence length of the acrylonitrile/methyl acrylate copolymer lies between the values of the homopolymers of acrylonitrile and methyl acrylate. respectively.
    Notes: Es wurden kritische Fällungsmittelkonzentrationen im System Poly(acrylnitril-co-methylacrylat)/N,N-Dimethylformamid/Acrylnitril viskosimetrisch bestimmt. Oberhalb der kritischen Fällungsmittelkonzentration tritt Gelbildung ein, die Viskosität wird zeitabhängig. Steigendes Molekulargewicht von Acrylnitril/Methylacrylat-Copolymeren führt zu steigender Gelbildungstendenz. Umgekehrt führt der Einbau von Methylacrylat als Comonomerez zur Verringerung der Neigung zur Gelbildung.An verdünnten Lösungen von Acrylnitril/Methylacrylat-Copolymeren, die 5,8 Gew.-% Methylacrylat enthielten, wurden Lichtstreuungs- und Viskositätsmessungen durchgeführt. Die Molekulargewichts-Grenzviskositäts-Beziehung gehorcht der Gleichung \documentclass{article}\pagestyle{empty}\begin{document}$$ [\eta ] = 1,15 \cdot 10^{-2} M_w^{0,83}$$\end{document} Die Abhängigkeit des Gewichtsmittels des mittleren Trägheitsradiusquadrats vom Molekulargewicht wird wiedergegeben durch die Beziehung: \documentclass{article}\pagestyle{empty}\begin{document}$$ \left\langle {r_w^2 } \right\rangle = 3,15 \cdot 10{\rm }^{{\rm 18}} M_w^{1.185} $$\end{document} Die Ergebnisse werden mit Werten von Fujisaki und Kobayashi an Polyacrylnitril verglichen.Aus der Molekulargewichtsabhängigkeit der Trägheitsradien und der Grenzviskositäten wurden die ungestörten Dimensionen berechnet. Aus diesen läßt sich die Persistenzlänge bzw. das statistische Fadenelement nach Kuhn angeben. Der Einbau von Methylacrylat in Acrylnitril-Copolymere erhöht die Kettenbeweglichkeit. Die Persistenzlänge von Acrylnitril/Methylacrylat-Copolymeren liegt zwischen der des Polyacrylnitrils und der des Polymethylacrylats.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975125
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  • 156
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    Simplified solution of the Kirkwood-Riseman equations for the intrinsic viscosity of a chain macromoleculeDedicated to Professor Dr. H. Mark on his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 441-444 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Gleichungen von Kirkwood und Riseman wurden gelöst durch eine Umordnung, die eine viel einfachere Lösung erlabut. Bei diesem nuen Verfahren muß man nureine einzige Matrize der Ordnung N invertieren (wobei N die Zhal der Kettenglieder bedeutet). Diese Umkehrung ist der schwierigste Schritt in dieser Methode. Die Resultate stimmen genau überein mit jenen des gewöhnlichen Verfahrens, aber der Aufwand ist wesentlich geringer.
    Notes: A minor rearrangement of the Kirkwood-Riseman equations puts them in a form more suitable for solution than the standard form. Solution then involves the inversion of a single matrix of order N (where N is the number of segments) as the most difficult step. The results are exactly the same as the standard procedure, but the work is simplified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975129
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  • 157
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    Field ionization and electron impact mass spectrometry of polymers and copolymers, 4.Part 3, cf.3. Aromatic polyethers.To Prof. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 471-484 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polyäther Poly(oxy-1,3-phenylen) (1), Poly(oxy-2,6-dimethyl-1,4-phenylen) (2), Poly(oxy-2-methyl-6-phenyl-1,4-phenylen) (3), Poly(oxy-2,6-diphenyl-1,4-phenylen) (4) und Poly(oxy-2,5-dimethoxy-1,4-phenylen) (5) wurden bei Temperaturen zwischen 563 K und 853 K im Direkteinlaß eines Massenspektrometers pyrolysiert. Die charakteristische Verteilung von monomeren und oligomeren Fragmenten zeigt, daß es sich um statistische Kettenspaltung handelt. Der Kettenspaltung, die primär zu Radikalen führt, folgen schnelle Stabilisierungsreaktionen, so daß hauptsächlich Fragmente mit Hydroxy- und Phenyl-Endgruppen in den Pyro-Feldionenmassenspektren (PFIMS) gefunden werden. Bei 2 und 3 werden durch das Sauerstoffatom in ortho-Stellung die Bindungen zwischen den Methylseitengruppen und den Phenylenringen der Hauptkette gelockert. Bei einer Spaltung der Hauptkette zwischen zwei Grundbausteinen kann eine der Spaltungsstelle benachbarte Methylgruppe des einen Bruchstücks zum entstandenen freien Ende des anderen übertragen werden. Auf diese Weise können sowohl Fragmente mit fehlender als auch solche mit zusätzlicher Methylgruppe gebildet werden. Während die Methoxygruppen in 5 relativ leicht abgespalten werden, verbleiben die Phenyl-Seitengruppen der Polyäther 3 und 4 überwiegend an den Phenylenringen der Hauptkette.
    Notes: The polyethers poly(oxy-1,3-phenylene) (1), poly(oxy-2,6-dimethyl-1,4-phenylene) (2), poly(oxy-2-methyl-6-phenyl-1,4-phenylene) (3), poly(oxy-2,6-diphenyl-1,4-phenylene) (4), and poly(oxy-2,5-dimethoxy-1,4-phenylene) (5) were pyrolyzed in the direct inlet system of a mass spectrometer at temperatures between 563 K and 853 K. Statistical chain splitting is confirmed by the characteristic distribution of the thermal degradation products, namely monomers and oligomers. Chain splitting, leading primarily to radicals, is followed by fast stabilization reactions. Therefore, the pyro-field ion mass spectra (PFIMS) show mainly fragments with hydroxy and phenyl end groups. In the polyethers 2 and 3, the oxygen atom in ortho position lowers the strength of the bonds between the methyl side groups and the phenylene rings of the backbone. On fragmentation between monomeric units, one of the methyl groups at the point of chain break has the chance to change place to the newly established free end of the other fragment. In this way, fragments with both lack and surplus of a methyl group will be obtained. While the methoxy groups of 5 are easily split off, the overwhelming majority of the phenyl side groups in the polyethers 3 and 4 remain at the phenylene rings of the main chain.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975132
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    Birefringence studies of the stress-induced crystallization of rubbersDedicated to Prof. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 579-597 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Änderung der Kristallinität als Funktion der Zeit und des Verstreckungsgrades von synthetischem cis-1,4-Polyisopren wird durch gleichzeitige Messung der Doppelbrechung und der Zugspannung untersucht. Die Ergebnisse werden mit Werten verglichen, die aus der durch die Kristallisation bedingten Abnahme der Zugspannung abgeschätzt wurden. Verschiedene Methoden zur Berechnung der Kristallinität aus den experimentellen Daten werden verglichen. Es kann gezeigt werden, daß diese Methode ein empfindliches, einfach zu handhabendes Verfahren zur Bestimmung der Kristallinität dieser Proben darstellt.
    Notes: The change in the fraction crystallinity with time and elongation of synthetic cis-1,4-polyisoprene is studied through simultaneous measurement of birefringence and stress. Results are compared with values estimated from the decrease in stress arising from the crystallization. Various methods for calculating the crystallinity from the data are compared. This method proves to be a sensitive, convenient method for determination of crystallinity of such samples.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975138
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    Änderung der festigkeitseigenschaften von trioxan/äthylenoxid-copolymeren durch beeinflussung der morphologieHerrn Prof. H. Mark mit den besten Wünschen zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 621-636 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The addition of certain organic and inorganic substances to copolymers of trioxane and ethylene oxide results in a decrease of the spherulite size of the copolymers. At the same time, not only an increase in hardness and tensile strength, but also in impact strength is observed. Light microscopic studies on microtomed sections of comparable regions of injection molded plates, dissolution experiments with γ-butyrolactone, and the investigation of native and HCl-etched and silver coated surfaces of fractured specimens support the hypothesis, that the fracture during dart drop impact is taking place at the interface of the spherulites. Experiments with different dyes dissolved in the polymer melt lead to the assumption, that an accumulation of low molecular weight additives (stabilizers, pigments) and of oligomers at the spherulite interface can occur and is responsible for the formation of weak sites in the crystalline structure. On the other hand, studies on the rate of spherulite growth exclude the possibility of accumulation of ethylene oxide rich copolymers at the spherulite interfaces.
    Notes: Durch Zusatz von bestimmten organischen oder anorganischen Substanzen kann die Sphärolithgröße von Trioxan/Äthylenoxid-Copolymeren verringert werden. Dies bewirkt nicht nur eine Erhöhung von Härte und Streckspannung, sondern führt auch zu einer Steigerung der Stoßfestigkeit. Aus lichtmikroskopischen Untersuchungen von Mikrotomschnitten aus vergleichbaren Bereichen von Spritzgußplatten sowie durch Löseversuche in γ-Butyrolacton und durch Untersuchungen der ursprünglichen sowie der mit HCl-Gas angeätzten und versilberten Bruchflächen wird die Hypothese gestützt, daß der Bruch beim Fallversuch überwiegend an den Sphärolithgrenzen erfolgt. Versuche mit in der Polymerschmelze gelösten Farbstoffen zeigen, daß eine Anreichung von niedermolekularen Zusätzen (Stabilisatoren, Pigmente) sowie von Oligomeren in den Bereich zwischen den einzelnen Sphärolithen erfolgen kann. Aus der Verfolgung des Sphärolithwachstums ergibt sich dagegen, daß keine Anreichung von äthylenoxidreichen Copolymerisaten an den Sphärolithgrenzen erfolgt. Die Anwesenheit der genannten niedermolekularen Substanzen an den Sphärolithgrenzen ist für die Ausbildung von Schwachstellen verantwortlich.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975140
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    Studies on hydrolysis reaction of model substances of cellulose in the presence of polymer catalysts, 1. Hydrolysis reaction of dextrin in the presence of poly(vinylalcohol-co-vinylsulfonic acid) (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 37-47 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Hydrolyse von Dextrin wurde in Gegenwart von Copolymeren aus Vinylalkohol und Vinylsulfonsäure untersucht, wobei im Vergleich mit Schwefelsäure eine leichte Beschleunigung der Reaktion eintrat. Mischungen aus Polyvinylalkohol und Polyvinylsulfonsäure bewirkten dagegen eine Verzögerung der Reaktion. Obwohl die Reaktionsge-schwindigkeiten mit fallendem Molekulargewicht des Substrates zunahmen, waren sie für alle Molekulargewichte bei Anwesenheit des Copolymeren größer als bei Anwesenheit von Schwefelsäure. In Gegenwart des Copolymeren waren die Aktivierungsenthalpie und die Aktivierungsentropie kleiner als für Schwefelsäure oder Äthansulfonsäure. Die Reaktionsbeschleunigung wurde durch die Abnahme von ΔH≠ verursacht, was schon früher für verschiedene Reaktionen in Gegenwart von Polyelektrolyten beobachtet wurde. Alle Aktivierungsparameter erfüllten die isokinetische Beziehung, was bedeutet, daß der Reaktionsmechanismus durch die Anwesenheit des Copolymeren nicht verändert wird.
    Notes: The hydrolysis of dextrin was studied in the presence of poly(vinyl alcohol-co-vinylsulfonic acid). The reaction was slightly accelerated by the copolymer in comparison with sulfuric acid. Mixtures of poly(vinyl alcohol) and poly(vinylsulfonic acid) retarded the reaction. Although the reaction rates tended to increase with decreasing molecular weight of the substrate, the reaction rates in the presence of the copolymer were always larger than in the case of sulfuric acid at the same molecular weight of the substrate. Both the enthalpy and entropy of activation in the presence of the copolymer were smaller than those for sulfuric acid or ethanesulfonic acid; the acceleration observed was due to the decrease of ΔH≠ as was noted earlier for a variety of reactions in the presence of polyelectrolytes. All of these activation parameters satisfied well the isokinetic relationship, indicating that the reaction mechanism was not changed by the presence of the copolymer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760104
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  • 161
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    Modellsubstanzen für polymere Redoxsysteme, 87. Mitteilung: cf.7.. Tetra- und hexavalente Redoxsysteme vom 1,4-Benzochinon-Typus (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 97-125 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The synthesis and properties of the following oligomeric redox systems are described: 2-(1,4-benzoquinone-2-ylmethyl)-5-methyl-1,4-benzoquinone (2b), the three isomeric bis(1,4-benzoquinone-2-ylmethyl)benzenes 8a, 9a and 10a and their homologues, the isomeric bis[2-(1,4-benzoquinone-2-yl)ethyl]-benzenes 8b, 9b and 10b. By 1H-NMR-spectroscopy the existence of 2-(2,5-dihydroxybenzyl)-1,4-benzoquinone (4) can be demonstrated, which reveals that in acidic solutions partly oxidized or reduced tetravalent redox systems of the quinone type molecules represent covalently bound quinone-hydroquinone systems. In contrast to the other compounds the partly reduced o-bis(quinone-2-yl) compound 8a easily forms an intramolecular charge-transfer complex in solution.The following totally symmetric hexavalent redox systems were synthesized as models for oxidation-reduction polymers: tris(1,4-benzoquinone-2-yl)methane (17), tris(1,4-benzo-quinone-2-ylmethy1)benzene (19a), and tris[2-(1,4-benzoquinone-2-yl)ethyl] benzene (19b).
    Notes: Es werden die Synthese und die Eigenschaften von 2-(1,4-Benzochinon-2-ylmethyl)-5-methyl-1,4-Benzochinon (2b), der drei isomeren Bis(1,4-Benzochinon-2-ylmethyl)benzole 8a, 9a und 10a und der drei hierzu homologen Bis[2-(1,4-Benzochinon-2-yl)äthyl]benzole 8b, 9b und 10b beschrieben. Sie stellen oligomere Redoxsysteme dar. Durch 1H-NMR-spektroskopischen Strukturbeweis von 2-(2,5-Dihydroxybenzyl)-1,4-Benzochinon (4) wird belegt, daß in saurer Lösung teiloxidierte tetravalente Redoxsysteme vom BenzochinonTypus ein miteinander verknüpftes Hydrochinon- und Chinonsystem darstellen. Die teilreduzierte, o-verknüpfte Bis(chinonyl)-Verbindung 8a bildet in Lösung leicht einen intramolekularen CT-Komplex, was bei den anderen Verbindungen nicht beobachtet wird.Als spezielle Modelle für Oxidations-Reduktions-Polymere wurden ferner drei völlig symmetrische, hexavalente Redoxsysteme synthetisiert und charakterisiert: Tris(1,4-Benzochinon-2-yl)-methan (17), Tris(1,4-Benzochinon-2-ylmethyl)benzol (19a) und Tris[2-(1,4-Benzochinon-2-yl)äthyl]benzol (19b).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760108
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  • 162
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    Determination of long-chain branching distribution in polyethylene by combination of gel permeation chromatography and viscometry (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 203-212 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die direkte Messung der Grenzviskositätszahl von Fraktionen aus der Gelpermeations-chromatographie wird mit dem Konzept der universalen Eichung kombiniert, um Langkettenverzweigung in Polyáthylen zu bestimmen. Das experimentelle Verfahren, einschließlich einer Diffusionsverbreiterungskorrektion für das begrenzte Auflösungsvermögen unseres chromatographischen Systems, wird beschrieben. Die Ergebnisse für drei verzweigte Polyäthylene werden mit den Ergebnissen verglichen, welche mit der Standardmethode (Präparative Kolonnenfraktionierung und Untersuchung der Fraktionen mit Lichtstreuung und Viskosimetrie) erhalten werden.
    Notes: Direct measurement of intrinsic viscosity on gel permeation chromatography effluent was combined with use of the universal calibration concept in order to determine long-chain branching in polyethylene. The experimental procedure, involving an axial dispersion correction for the limited resolution of our chromatographic system, is presented. Results obtained for three branched polyethylene samples are compared with those provided by the well-established method of preparative fractionation by column elution and examination of the fractions by viscometry and light scattering.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760115
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  • 163
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    Ein einfacher, UV-photometrischer Nachweis der Übertragungsreaktion von aliphatischen Azoverbindungen an Polystyrol (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 229-231 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760118
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  • 164
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    Effect of molecular weight distribution of the original polymer on separation characteristics in successive solutional fractionation (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1051-1069 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde versucht, den Einfluß der Molekulargewichtsverteilung (MGV) des Ausgangspolymeren auf die Trenncharakteristik bei der sukzessiven Lösefraktionierung (SSF) aufzuklären, außerdem wurden Vergleiche mit der sukzessiven Fällungsfraktionierung (SPF) angestellt. Polymere mit Schulz-Zimm und mit Wesslau-Verteilungen des Polymerisationsgrads, deren Quotient von Gewichts- zu Zahlenmittel-Polymerisationsgrad X̄0w/X̄0n sich von 2 bis 5 erstreckte, wurden in Lösung gebracht und abgekühlt, um eine Fällung nach der modifizierten Simulationsprozedur von Kamide und Sugamiya hervorzurufen, die auf der Theorie von Flory-Huggins für verdünnte Lösungen von Polymeren beruht. Bei der SSF wurden in den Fraktionen keine Zwei-Maxima-Verteilungen beobachtet, wenn die gleichen Bedingungen angewandt wurden, die bei der SPF Zwei-Maxima-Verteilungen ergeben. Der niedrigste X̄w,-Wert für die Fraktionen ist bei einem vorgegebenen Versuch fast derselbe für SSF und SPF, wobei das Minimum mit abnehmendem X̄0w/X̄0n (der Index 0 bezeichnet das Ausgangspolymere) zunimmt. Der- Quotient X̄0w/X̄0n, der Fraktionen wird durch X̄0w/X̄0n; nicht stark beeinflußt, wenn man von den ersten Fraktionen absieht. Die Standardabweichung σ′ der MGV der Fraktionen nimmt zu Anfang mit zunehmendem X̄0w/X̄0n, ab, zum Ende der Fraktionierung kehrt sich dieses Verhalten urn. Im allgemeinen liefert die SSF scharfe Fraktionen unabhängig von X̄0w/X̄0n.
    Notes: An attempt has been made to clarify the effect of molecular weight distribution (MWD) in the original polymer on the separation characteristics in successive solutional fractionation (SSF) and comparisons were made with successive precipitational fractionation (SPF). Polymers with Schulz-Zimm distribution and Wesslau distribution of the degree of polymerization (ratio of the weight- to number-average degree of polymerization, X̄0w/X̄0n = 2 to 5) were brought into solution, and cooled to cause precipitation according to the modified simulative procedure of Kamide and Sugamiya, based on the Flory-Huggins's theory of dilute solutions of polymers. No double-peak distributions were observed in the fractions obtained by SSF under the conditions which give double-peak distributions in the case of SPF. The minimum value of X̄w in the fractions obtained in a given run is almost the same for SSF and SPF, the minimum increasing with decreasing X̄0w/X̄0n (the suffix zero denoting the original polymer). The ratio X̄w/X̄n in the fractions is not greatly influenced by X̄0w/X̄0n except for the first few fractions. The standard deviation σ′ of the MWD in the fractions decreases with increasing X̄0w/X̄0n in an initial stage, while this situation is reversed in the later stages. In general SSF furnishes sharp fractions regardless of X̄0w/X̄0n.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760417
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  • 165
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    Orientation of propylene units in polypropylene and ethylene/propylene copolymers (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1121-1128 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Äthylen-Propylen Copolymere, die mit spezifisch syndiotaktischen Katalysatoren dargestellt werden, enthalten sowohl Kopf-Schwanz als auch Schwanz-Kopf orientierte Propyleneinheiten. Daher ist diese Copolymerisation eigentlich eine Terpolymerisation und die einfache Propylenpolymerisation eine binäre Copolymerisation.Die sich daraus für die Kinetik der Polymerisation und Copolymerisation ergebenden Konsequenzen werden untersucht.
    Notes: Ethylene-propylene copolymers prepared with syndiotactic specific catalysts contain both head-to-tail and tail-to-head oriented propylene units. Consequently, this copolymerization is, actually, a terpolymerization, and the propylene polymerization is a binary copolymerization.The consequences of this fact on the kinetics of polymerization and copolymerization are considered.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760419
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  • 166
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    Evaluation of triads in methyl methacrylate/methacrylic acid copolymers by 1H-NMR in different solvents and 13C-NMR (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1071-1119 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Wahrscheinlichkeiten der kompositiv-konfigurativen Triaden in taktischen und ataktischen Methylmethacrylat/Methacrylsäure-Copolymeren werden ermittelt. Nach Sicherung der Zuordnung von syndiotaktischen und isotaktischen Triaden in den 1H-NMR Spektren der taktischen Copolymeren in drei NMR-Lösungsmitteln werden die chemischen Verschiebungen der heterotaktischen Triaden mit Hilfe von Verschiebungsinkrementen postuliert. Die postulierte Zuordnung der heterotaktischen Triaden wird gestützt durch den Vergleich der experimentell gefundenen 1H-NMR Peak-Intensitäten von ataktischen Methylmethacrylat/Pentadeuteromethacrylsäure-Copolymeren und Pentadeuteromethylmethacrylat/Methacrylsäure-Copolymeren in drei Lösungsmitteln mit den berechneten Triadenwahrscheinlichkeiten. Die zur Berechnung der Triadenwahr-scheinlichkeiten notwendigen kompositiven und konfigurativen Größen werden ermittelt. Es wird gezeigt. wie die Peak-Flächen in den Spektren der partiell deuterierten Copolymeren in verschiedenen Lösungsmitteln miteinander kombiniert werden können, urn die Wahrscheinlich keiten der kompositiv-konfigurativen Triaderi in ataktischen Copolymeren zu ermitteln. Möglichkeiten ziir Auswertung von Triadenwahrscheinlichkeiten aus den 13C-NMR Spektren von taktischen und ataktischen Methylmethacrylat/Methacrylsäure Copolymeren werden aufgezeigt.
    Notes: The probabilities of compositional-configurational triads in tactic and atactic methyl methacrylate/methacrylic acid copolymers are evaluated. After verification of the assignment of syndiotactic and isotactic triads in the 1H-NMR spectra of tactic methyl methacrylate/methacrylic acid copolymers in three NMR solvents, the chemical shifts of the heterotactic triads are postulated by shift increments. The postulated assignment of the heterotactic triads is supported by comparison of the experimental 1H-NMR peak intensities of atactic methyl methacrylate/pentadeuteromethacrylic acid copolymers and atactic pentadeuteromethyl methacrylate/methacrylic acid copolymers in three NMR solvents with calculated triad probabilities. The compositional and configurational parameters needed for the calculation of triad probabilities are determined. It is shown how the peak areas obtained from the two partially deuterated, atactic copolymers in different solvents may be combined to determine the probabilities of all compositional-configurational triads in atactic copolymers. Possibilities for the evaluation of triad probabilities from the 13C-NMR spectra of tactic and atactic methyl methacrylate/methacrylic acid copolymers are presented.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760418
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  • 167
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    A quantum-chemical study of the preferred conformations of the model compounds of polypropylene (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1151-1161 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unter Berücksichtigung ihrer stereochemischen Konfigurationen und der Vorzugskonformationen wurden die Gesamtenergien einiger Modellsubstanzen für Polypropylen (PP) quantenchemisch nach der CNDO/2-Methode berechnet.Um die Informationen zur Konformation und Konfiguration von PP zu erhalten, wurden für 2-Methylbutan und Pentan die statistischen Gewichte, τ und ω, abgeschätzt und mit den aus semiempirischen Potentialfunktionen erhaltenen verglichen. Darüberhinaus wird gezeigt, daß sich die Form der Potentialkurven nahe dem Energieminimum für die Vorzugskonformationen mancher Modellsubstanzen - wie des Dimeren, Trimeren und Tetrameren - deutlich unterscheidet. Es ist also bezüglich des Modells der rotationsisomeren Zustände Vorsicht bei der Anwendung auf PP und seine Modellsubstanzen angebracht.
    Notes: The total energies of some model compounds for polypropylene (PP) were calculated quantum-chemically with the CNDO/2 method, taking into account their stereochemical configurations and preferred conformations.The statistical weights, τ and ω, are estimated using 2-methylbutane and pentane, respectively and are compared with those obtained with semiempirical potential functions, in order to obtain informations on the conformation and configuration of PP. Moreover, it is pointed out that the shape of the potential curves nearby the energy-minimum state is considerably different among the preferred conformations in some model compounds, such as dimer, trimer, and tetramer and this result demonstrates that one should be cautious with the application of the rotational isomeric state model to PP and its model compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760421
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  • 168
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    Thermal behaviour of poly[imino(1-oxooctamethylene)], nylon 8 (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1163-1171 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das thermische Verhalten von Nylon 8 wurde durch Differentialkalorimetrie (DSC) untersucht. Glasübergangstemperaturen (Tg) wurden im Molekulargewichtsbereich 1,7·103 - 3,4·104 gemessen, um eine Tg-Mn Abhängigkeit zu bestimmen. Eine kleine Verminderung der Tg-Werte wurde für die Proben mit den niedrigsten Molekulargewichten beobachtet: diese Proben wurden jedoch durch Polymerisation in Gegenwart eines Kettenabbruchreagenzes erhalten.Weiterhin wurde der Ursprung der mehrfachen Schmelzpeaks, die man während der DSC Analyse von unter verschiedenen Bedingungen kristallisierten Proben beobachtet, erforscht. Die Abhängigkeit des Schmelzverhaltens von der Aufheizgeschwindigkeit, der Abkühlungsgeschwindigkeit aus der Schmelze und von der isothermen Kristallisation bei verschiedenen Kristallisationstemperaturen (Tc) steht in Einklang mit der Hypothese eines Schmelz-Rekristallisationsprozesses während des Aufheizens.
    Notes: The thermal behaviour of nylon 8 was studied by differential scanning calorimetry (DSC). Glass transition temperatures (Tg) were measured over the molecular weight range 1,7·103 - 3,4·104 in order to determine a Tg-Mn dependence. A small decrease in the Tg values was observed for the lowest molecular weight samples which, however, were obtained by polymerization in presence of a chain terminator.The origin of multiple melting endotherms, found during DSC analysis of samples crystallized under different conditions, was also investigated. The effects of heating rate, of cooling rate from the melt, and of isothermal crystallization at various crystallization temperatures (Tc) on melting behaviour were consistent with the hypothesis of a meltrecrystallization process during heating.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760422
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  • 169
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    Gleichgewichtsdrücke, Löslichkeit und Mischbarkeit des systems aus Polyäthylen niedriger dichte und Kohlenwasserstoffen bzw. halogenierten KohlenwasserstoffenHerrn Prof. Dr. H. Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 415-439 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Diffusion and solubility of hydrocarbons and halogenated hydrocarbons in low density polyethylene for temperatures between 20°C and 150°C were determined by sorption-, equilibrium vapour pressure-, and gaschromatographic measurements. The coefficients of permeation, diffusion and of Bunsen's solubility were calculated from the experimental data. The corresponding energies of activation and enthalpies of solution and mixing follow from the dependences of these coefficients on the temperature. For further interpretation the theories of Flory, Huggins, Prigogine and Patterson were used. Phase diagrams showed that infinite solubility lies between the limits of the upper and lower miscibility gap and above the melting point curve of the crystallites.
    Notes: In Sorptionsversuchen wurden Diffusion und Löslichkeit von Kohlenwasserstoffen und halogenierten Kohlenwasserstoffen in Polyäthylen niedriger Dichte bei Temperaturen zwischen 20°C und 150°C bestimmt. Gleichgewichtsdampfdruck- und gaschromatographische Löslichkeitsmessungen ergänzten die Ergebnisse der Sorptionsexperimente. Aus den gewonnenen Daten wurden die Permeations-, Diffusions- und Bunsenschen Löslichkeitskoeffizienten und deren Temperaturabhängigkeiten errechnet. Letztere führten zu den entsprechenden Aktivierungsenergien, zu den integraden Lösungs- und differentiellen Mischungswärmen. Die Anwendung dieser Meßwerte erfolgte auf theoretische Ansätze von Flory, Huggins, Prigogine und Patterson. Phasendiagramme zeigten, daß das Gebiet unbegrenzter Mischbarkeit durch die obere und untere Mischungslücke, sowie durch die Kristallitschmelzpunktskurve abgegrenzt wird.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975128
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  • 170
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    The vibrational spectrum of crystalline syndiotactic. Poly(vinyl chloride)Dedicated to Prof. Dr. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 491-506 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde eine Normal-Schwingungsanalyse für kristallines syndiotaktisches Poly(vinyl-chlorid) sowie seine deuterierten Derivate durchgeführt. Diese basierte auf einem allgemeinen Valenzkräftefeld (valence force field), das aus einer Spektrenanalyse von kleinen Molekülen sekundärer Chloride abgeleitet wurde. Die Berechnungen erlauben - auch für das Gebiet niedriger Frequenzen - eine sehr befriedigende Zuordnung der beobachteten Banden in den IR- und Ramanspektren.
    Notes: A normal vibration analysis has been carried out for crystalline syndiotactic poly(vinyl chloride) and its deuterated derivatives. This was based on a general valence force field derived from an analysis of the spectra of small secondary chloride molecules. The calculations permit a very satisfactory assignment to be made of the observed bands in the IR and Raman spectra, including the low frequency region.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975134
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  • 171
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    Microparacrystallites and paracrystalline superstructuresDedicated to Prof. Dr. Hermann Mark on his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 559-577 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hermann Mark hat 1940 darauf hingewiesen, daß es bis dahin noch keine einwandfreie Methode gab, die es gestattete, die durch Teilchengröße hervorgerufene Verbreiterung der Interferenzpunkte von der Verbreiterung durch Gitterfehler in einem Polymeren zu trennen. In der üblichen Darstellung wird auch vielfach bis heute noch von «kristallinen» und «amorphen» Bereichen innerhalb eines Polymeren gesprochen. Daß innerhalb dieser sog. kristallinen Bereiche Gitterstörungen einer besonderen Art existieren, die von großer Bedeutung für die Stoffeigenschaften sind, wird oft außer Betracht gelassen. Im folgenden wird gezeigt, wie man diese Störungen nach der Theorie des Parakristalls quantitativerklären kann. Auf eine Reihe von Mißverständnissen, die inzwischen in der Literatur aufgetaucht sind, wird hingewiesen. Schließlich werden kurz einige Resultate diskutiert, die mit Hilfe dieser Theorie über die Struktur synthetischer Polymere gewonnen wurden.
    Notes: Hermann Mark pointed out in 1940H. Mark “Allgemeine Grundlagen der Hochpolymeren Chemie” Akad. Verl. Ges. Leipzig, S. 203 (1940). that up to then there did not exist a relevant method for the quantitative evaluation of the size and the lattice distortion of coherently scattering domains in a polymer. Until now usually one speaks of “crystalline” and “amorphous” domains within a polymer. The domains which scatter coherently are considered to be crystalline and it is out of consideration, that lattice distortions exist which are of fundamental interest in the understanding of the properties of polymers. It is the aim of this contribution to show that these distortions can be explained quantitatively by the theory of paracrystals. A series of misunderstandings are discussed which exist in the literature. Some results of the application of this theory to synthetic polymers are discussed which seem to be of fundamental interest.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975137
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  • 172
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    Crystal structure and morphology of polymers from solid-state reactionsDedicated to Professor Dr. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 521-558 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Einige Festkörperrcaktionen. die zur Bildung von Polymer-Kristallen führen. werden diskutiert und es wird gezeigt, wie man die Ergebnisse der morphologischen Untersuchungen dazu verwenden kann, den Mechanismus der Festkörperpolymerisation aufzuklären. Beispiele für die folgenden drei Mechanismen werden im einzelnen behandelt: (a) Kristallisation der makromolckularen Ketten nach der Polymerisation, (b) simultane Polymerisation und Kristallisation, (c) Polymerisation in fester Lösung.Als ein Beispiel für Kristallisation nach bereits erfolgter Polymerisation wird die Morphologie von Ziegler-Natta Olefin-Polymerisaten diskutiert. Ein anderes Beispiel dafür liefert die kationische Polymerisation von 1,3,5-Trioxan aus Lösungen. Es wird gezeigt. daß in diesem Fall das System einem thermodynamischen Gleichgewicht zwischen der kristallinen Phase des Polymeren und dem gelösten Monomeren zustrebt. Dabei findet durch Aufbrechen der Kettenfalten und Einbau von Monomereinheiten ein Dickenwachstum der Kristalle statt, das schließlich zur Entstehung von gestrecktkettigen Kristallen durch diese Transacctalisierung führt.Die durch Bestrahlung oder katalytisch induzierte Festkörperpolymerisation von 1,3,5-Trioxan oder 1,3,5,7-Tetroxan stellt ein Beispiel für simultane Polymerisation und Kristallisation dar. Einige molekulare Modelle für das Wachstum der Ketten werden auf Grund der morphologischen Beobachtung entwickelt. Es zeigt sich, daß bei diesen Reaktionen im allgemeinen keine wirklichen gestrecktkettigen Kristalle des Poly(oxymethylen)s. (POM) entstehen; Ursache dafür ist entweder Kettenfaltung (Dichtefluktuation entlang der Faserachse) oder Zwillingsbildung (Orienticrungsfluktuation). Art und Ursprung der Zwillingsbildung von POM aus kristallinem 1,3,5-Trioxan wird im einzelnen erörtert.Die topochemische Polymerisation von Monomeren mit konjugierten Dreifachbindungen gibt ein Beispiel für Polymerisation in fester Lösung. Die Polymerketten wachsen als isolierte Einheiten im Gitter des Monomeren. In einigen Fällen kann das gesamte Monornere ohne Phasentrennung umgesetzt werden. Dadurch entstehen makroskopische Polymer-Einkristalle aus gestreckten Ketten. die bisher noch nicht auf andere Weise dargestellt werden konnten.
    Notes: Some solid-state reactions which give rise to the formation of polymer crystals are discussed and the observation of the nascent polymer morphology is used as a guide-line to learn about the reaction mechanism of solid-state polymerizations. Examples for the following three different mechanisms are treated in detail: (a) crystallization succeeding polymerization, (b) simultaneous polymerization and crystallization, and (c) polymerization in solid solution.The nascent morphology of poly(alkylene)s obtained by Ziegler-Natta catalysis is taken as an example for crystallization succeeding polymerization. Another example is the cationic polymerization of 1,3,5-trioxane from solution. In this case a thermodynamic equilibrium between the phases of the solid crystalline polymer and the dissolved monomer is approached; here, by breaking up chain folds and insertion of monomeric units, an increase in thickness of the crystals takes place, which finally leads to extended chain crystals by this transacetalization.The solid-state polymerization of 1,3,5-trioxane and 1,3,5,7-tetroxane as induced by high-energy radiation or catalysts is described as an example for simultaneous polymerization and crystallization. Possible molecular models of the chain growth are developed on the basis of the morphological observations. Truly extended chain crystals of poly(oxymethylene), (POM), cannot be obtained generally from solid 1,3,5-trioxane or 1,3,5,7-tetroxane; the reason for this is either chain-folding (density fluctuation along the fibre axis) or “twin”-structure formation (orientation fluctuation). The nature and origin of the “twin”-structure of POM from crystalline 1,3,5-trioxane is discussed in detail.Topochemical polymerization of monomers with conjugated triple-bonds is an example for polymerization in solid solution. The polymer chains grow as isolated macromolecules within the monomer lattice. Since quantitative conversion can be reached in some cases without phase separation, this comprises a method to produce macroscopic, extended chain polymer single crystals, which so far could not be prepared by another method.
    Additional Material: 28 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975136
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    Studies on functional micelles, 2Part 1, cf.1.. Micellar effect on the preparation of cyclic dipeptide from thioalanine S-dodecyl ester (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 49-56 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Kondensationsreaktion von Thioalanin-S-dodecylester (1a) in wäßrigem Medium unter Katalyse von Pyridin, Natriumhydroxid oder Alkylaminen, ergab in guter Ausbeute 3,6-Dimethyl-2,5-piperazindion (2a), obwohl Thioalanin-S-äthylester (1b) unter denselben Reaktionsbedingungen nur Spuren eines cyclischen Dipeptids 2a ergab. Dieser Beschleunigungseffekt wurde mit der Annahme einer Matrizenreaktion an der Mizellenoberfläche erklärt.
    Notes: The condensation reaction of thioalanine S-dodecyl ester (1a), catalyzed by pyridine, sodium hydroxide or alkyl amines, was carried out in aqueous media to give 3,6-dimethyl-2,5-piperazinedione (2a) in good yield, although thioalanine S-ethyl ester (1b) gave under the same reaction conditions only traces of cyclic dipeptide 2a. The specific accelerating effect was explained by a supposed matrix reaction on the micelle surface.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.021760105
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    NMR-Untersuchungen an Polyacetalen, 43. Mitteilung: cf.9.. Sequenzanalyses von Homo- und Copolymeren des 1,3,5-TrioxepansHerrn Prof. Dr. H. Mark mit freundlichen Grüßen und besten Wünschen zum 80. Geburtstag gewidmet. (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 235-247 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 1,3,5-Trioxepane (1) undergoes very easily the cationic polymerization. From 1H-NMR-spectra (triads) and form 13C-NMR-spectra in the presence of Eu(fod)3 (pentads and heptads) it follows that the microstructure of polytrioxepane is identical with random 1,3,5-trioxane (2)/1,3-dioxolane (3)-copolymers. A mechanism of the homopolymerization of 1 is discussed. 1 is incorporated preferentially during the copolymerization with 3.
    Notes: 1,3,5-Trioxepan (1) ist kationisch leicht polymerisierbar. Aus den 1H-NMR-Spektren (Triadensequenzen) und den 13C-NMR-Spektren unter Zusatz von Eu(FOD)3 (Pentaden-und Heptadensequenzen) wird deutlich, daß die Mikrostruktur von Polytrioxepan identisch ist mit 1,3,5-Trioxan (2)/1,3-Dioxolan (3)-Copolymeren. Ein Mechanismus für die Polymerisation von 1 wird diskutiert. Bei der Copolymerisation mit 3 wird 1 bevorzugt in das Copolymere eingebaut.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975116
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    Conformational transitions of soybean trypsin inhibitor incited by alkyl sulfates of various hydrophobic chain lengthDedicated to Professor Dr. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 275-282 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Veränderungen der Konformation des Trypsin-Inhibitors (STI) (aus Sojabohnen) wurden in Gegenwart von Natriumoctyl-, -decyl-, -dodecyl- und -tetradecylsulfat mit der Methode des Cirkulardichroismus (CD) untersucht. Durch ausreichend hohe Konzentrationen der Alkylsulfate wurde das Erscheinen von CD-Banden hervorgerufen, die auf das Entstehen von α-Helix und β-Struktur hinweisen. Die CD-Banden im nahen Ultraviolett wurden stark reduziert. Der Logarithmus des Molverhältnisses Alkylsulfat/Protein, das 50% des 220 nm Übergangs hervorruft, verminderte sich linear mit wachsender Zahl der CH2-Gruppen in dem Alkylrest. Die Molverhältnisse Alkylsulfat/STI, die zum Verschieben der aromatischen Seitenketten nötig waren (z. B. CD bei 294 und 275 nm) waren niedriger als jene, die die Polypeptidhauptkette beeinflußten und sie erniedrigten sich stark mit wachsender Länge der Alkylgruppe des Natriumalkylsulfats. Die Resultate weisen darauf hin, daß die dreidimensionale Struktur des STI hauptsächlich durch hydrophobe Wechselwirkungen stabilisiert wird.
    Notes: The conformational transitions of soybean trypsin inhibitor (STI) were studied in the presence of sodium octyl, decyl, dodecyl, and tetradecyl sulfates by means of circular dichroism (CD) measurement. Sufficiently high concentrations of the alkyl sulfates induced the formation of CD bands indicative of the α-helical and β-structures. The CD bands in the near ultraviolet zone were strongly reduced. The logarithm of moles alkyl sulfate per mole protein, that produced 50% of the transition corresponding to the CD bands at 220 nm, decreased linearly with the increasing numbers of CH2 groups in the alkyl radical. The mole ratios of the alkyl sulfate needed to dislocate the aromatic side chains (CD e.g. at 294 and 275 nm) were lower than those affecting the polypeptide backbone, and they decreased strongly with the increasing chain length of the alkyl chain of the sodium alkyl sulfate. The results indicate that the three-dimensional structure of the macromolecule of STI is stabilized chiefly by hydrophobic interactions.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975119
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  • 176
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    Bestimmung der Diffusionskoeffizienten von Polymeren in Lösungen bis zu mittleren Konzentrationen durch inelastische LichtstreuungHerrn Prof. Dr. H. Mark aus Anlaß seines achtzigsten Geburtstages gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 359-366 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The method of inelastic light scattering is extended to the region of moderate concentrations (up to 8%). Measurements on a narow distributed polystyrene of Mw = 670000 in toluene at 20°C and in cyclohexane at 35°C are reported. For comparison the same photometer also is used for elastic light scattering measurements, which compare well with former results.The diffusion coefficients observed by inelastic light scattering are qualitatively comparable to those obtained by Rehage and Ernst on similar systems, who used classical
    Notes: Die Methode der inelastischen Lichtstreuung wird bis in den Bereich mittlerer Konzentration (8%) ausgedehnt. Gemessen wird ein Polystyrol enger Molekulargewichtsverteilung mit Mw = 670000 in Toluol bei 20°C sowie in Cyclohexan bei 35°C. Zur Kontrolle werden mit dem gleichen Gerät auch elastische Lichtstreuungsmessungen ausgeführt, die sich mit früheren Untersuchungen in Übereinstimmung bringen lassen.Die Diffusionskoeffizienten aus der inelastischen Lichtstreuung stimmen qualitativ mit denen aus klassischen Diffusionsmessungen überein, die Rehage und Ernst an ähnlichen Systemen ausführten. Bei verdünnten Lösungen zeigte sich im betrachteten Winkelbereich ein linearer Zusammenhang zwischen 2Γ und sin2 ∂/2. Mit zunehmender Konzentration wurde in diesen Auftragungen eine Aufwärtskrümmung sichtbar, die vom Fremdkorrelationsanteil in der Paarverteilungsfunktion herrühren sollte. Die Konzentrationsabhängigkeit des Diffusionskoeffizienten bleibt im gesamten betrachten Konzentrationsbereich für Toluol positiv und für das Θ-Lösungsmittel Cyclohexan negativ. Mit wachsender Konzentration nimmt diese Konzentrationsabhängigkeit ab.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975124
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    Intrinsic stress tensor of polymer solutions in laminar flow. Modified elastic dumb-bell model with hydrodynamic interactionDedicated to Prof. H. F. Mark at his 80th anniversary (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 453-470 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: An Hand des vereinfachten Perlschnur- oder des äquivalenten modifizierten elastischen Hantelmodells unter Berücksichtigung der hydrodynamischen Wechselwirkung zwischen den Segmenten und deren Änderung als Folge der Knäuelverformung wurde der Eigenspannungstensor in laminarer Strömung mit Transversal- und Parallelgradienten als Funktion des Gradienten \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} und des dimensionslosen Gradientenparameters β berechnet. Die durch die Strömung verursachte Streckung des Gauß'schen Knäuels macht sich zuerst in einer Erhöhung und nachher in einer Erniedrigung der hydrodynamischen Wechselwirkung bemerkbar. Als Folge davon sinken als Funktion des Gradienten vorerst die Viskositätszahl [η]tr von ausreichend langen Makromolekülen und der effektive mittlere hydrodynamische Widerstandskoeffizient des Einzelsegmentes Λ bis zu einem Minimum ab, um nachher wesentlich langsamer anzusteigen. In der laminaren Strömungmit Parallelgradienten äußert sich dieser Effekt in einer Verformungsinstabilität, die eventuell einc Rolle in der durch minimale Polymerzusätze verursachten Widerstandsver-minderung des turbulenten Flielßens spielt. Die Existenz dieser zwei eng verknüpften Phänomene kann nur durch Experimente bewiesen oder widerlegt werden. Im letzteren Falle kann man vermuten, daß die Vernachlässigung der sicher vorhandenen Anisotropie der hydrodynamischen Wechselwirkung in fast allen bisherigen Betrachtungen dic Haupt-verantwortung fur die fehlerhafte Voraussage der hydrodynamischen Effekte verdünnter Lösungen zu tragen hat.
    Notes: The simplified necklace or the equivalent modified elastic dumb-bell model with consideration of hydrodynamic interaction among the beads and its change with coil expansion was used for the calculation of the intrinsic stress tensor in laminar flow with transverse and parallel gradient as function of the conventional gradient \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} and the dimensionless gradient parameter β. The expansion of the Gaussian coil in flow first increases and then decreases the hydrodynamic interaction. As a consequence the intrinsic viscosity [η]tr of sufficiently large macromolecules and the effective average hydrodynamic resistance coefficient Λ of the bead show first a decrease to a minimum and a subsequent gradually slower increase with the gradient. In laminar flow with parallel gradient this effect yields a deformational instability which may play some role in drag reduction of turbulent flow by polymer additives. Experimental evidence will have to conform or to refute these two interdependent phenomena. In the latter case, one suspects that the neglect of anisotropy of hydrodynamic interaction is the main cause of the unrealistic predictions of intrinsic hydrodynamic properties of polymer solutions.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975131
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    IR-Untersuchung der Blockstruktur von 2-substituierten Propen-CopolymerenHerrn Prof. Dr. H. Mark zum 80. Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 507-520 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In the infrared spectra of 2-substituted propene(1)-copolymers —(CH2—C(CH3)R)—(R = CH3, C6H5, CN, COOR) with styrene or acrylonitrile, an intensive absorption at 1250-1200 cm-1 was observed, from which conclusions concerning the length of the 2-substituted propylene sequences can be drawn. With a length of at least 5 monomeric units the band is reaching its full intensity. The high intensity is probably due to vibrational coupling within a favoured chain conformation (T+G′+T+G′+ or T+T+G′+G′+) (T = trans, G = gauche) which is stabilized by the voluminous CH3- and R-groups. With decreasing sequence length, the intensity of this band is decreasing, too. At the same time the band position is shifted to higher wave numbers. The band is assigned to C—C(CH3)R—C skeletal vibrations. In case of isolated units, the mode is comparable with the n3 (type F) skeletal vibration of neopentane.
    Notes: In den IR-Spektren von 2-substituierten Propen (1)-Copolymeren des Typs —(CH2—C(CH3)R)—(R = CH3, C6H5, CN, COOR) mit Styrol bzw. Acrylnitril wurde im Bereich 1250-1200cm-1 eine intensive Absorption gefunden, die Aussagen über die Länge der 2-substituierten Propylen-Sequenzen gestattet. Die für das Erreichen der vollen Bandenintensität notwendige Sequenzlänge liegt bei ca. 5 Monomereinheiten. Die große Intensität weist auf Schwingungskopplung innerhalb einer bevorzugten Kettenkonformation (T+G′+T+G′+oder T+T+G′+G′+) (T = trans, G = gauche) hin, die durch das große Volumen der CH3- und R-Gruppen stabilisiert wird. Bei kürzeren Sequenzlängen nimmt die Intensität der Bande, bei gleichzeitiger Verschiebung nach höheren Wellenzahlen, ab. Die Bande wird der C—C(CH3)R—C-Gerüstschwingung zugeschrieben, wobei die Schwingungsart der isolierten Einheit etwa der n3 (Typ F)-Skelett-Schwingung von Neopentan entspricht.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.020011975135
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  • 179
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    Grafting of acrylic acid onto methylcellulose (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1-7 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Pfropfcopolymerisation von Acrylsäure auf Methylcellulose mit Kaliumpersulfat als Initiator wurde untersucht. Dabei wurden die verschiedenen Variablen, die das Ausmaβ der Pfropfung bestimmen, sowie die Löslichkeit der Pfropfcopolymere in verschiedenen Lösungsmitteln und Lösungsmittelgemischen untersucht. Copolymere, bei denen mehr als 20% Acrylsäure aufgepfropft waren, wurden in Wasser unlöslich.
    Notes: Grafting of acrylic acid onto methylcellulose backbone was studied using potassium persulfate as initiator. Different variables affecting the extent of grafting were studied. The copolymers with more than 20% grafting became insoluble in water. The solubility of the graft copolymer in different solvents and mixed solvents was studied.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760101
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    Thermische spaltungsmechanismen in homo- und copolymeren aus α-olefinen, 2.1. Mitteilung: cf.5.Herrn Professor Dr. H. Witte zum 65. Geburtstag gewidmet.Polypropylene mit bekannter taktizität, polyisobutylen und poly(1-buten)Auszug aus der Dissertation, M. Seeger, Frciburg 1972. Teile dieser Arbeit wurden vorgetragen: Dechema-Ausschußtagung, Frankfurt a. M., 18. 2. 1972. International Symposium on Macromolecules (IUPAC), Helsinki (Finnland), 1972, Preprint IV-32, vol. 5, p. 177. Euroanalysis I, Heidelberg, 1972. (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2059-2078 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polypropylene samples with known tacticity were investigated by pyrolysis with simul-taneous hydrogenation of the fragments and by temperature programmed gaschromato-graphy. The aim was to extend the knowledge on the degradation at elevated temperatures and the determination of the configurational sequence distributions.The fragment distribution may be explained-like the one of polyethylene-by assuminga superposition of a statistical and a nonstatistical scisson. From the shape of fragment distribution in the long fragment region the probability of a statistical scisson of a C-C bond in the chain was found to be a=0,15 (±0,02). This value is independent of the tacticity.By isomerization during thermal degradation the configuration in the fragments differs from that in the original chain. Therefore, with this method the tacticity can only be determined by comparison with known samples. Based on the statistics of isomerization and the preferably formed fragments it may be shown, that isomerization is caused mainly by stepwise transfer of radicals in the cyclisation process. This mechanism is particulary dominant in isotacric polypropylene at moderate pyrolysis temperature.Also in polyisobutylene, [poly( I,l-dimethylethylene)], and poly( 1-butene), [poly(l-ethyl-ethylene)], a primary statistical scisson can be determined from the fragment distribution. The frequencies of scisson have the same numerical value as in polypropylene. It was found to be essential for the stabilisation of the fragments in thermal degradation of vinyl polymers, that enough hydrogen for the intramolecular cyclisation is available. A lack in disposable hydrogen leads in the case of polyisobutylene to the well-known high yield in monomer, though fragments up to the octamers could be identified as well.
    Notes: Polypropylene mit bekannter Taktizität wurden durch Pyrolyse mit angeschlossener Hydrierung der Fragmente und temperaturprogrammierter Gaschromatographie untersucht. Ziel war eine Erweiterung der bei Polyäthylen gewonnenen Kenntnisse über den Abbau bei erhöhten Temperaturen sowie die Bestimmung konfigurativer Sequenzverteilungen.Die Fragmentverteilung läßt sich  -  wie die von Polyäthylen  -  aus der Überlagerung einer statistischen und einer nichtstatistischen Spaltung interpretieren. Aus dem Verlauf der Fragmentverteilung im Bereich langer Bruchstücke ergibt sich unabhängig von der Taktizität eine Wahrscheinlichkeit a=0,15 (±0,02) für die statistische Spaltung einer kettenständigen C - C-Bindung.Durch Isomerisierung beim thermischen Abbau weicht die Konfiguration in den Spaltstücken von der in der ursprünglichen Kette ab. Die Taktizität läßt sich daher mit dieser Methode nur nach einer Eichung bestimmen. Auf Grund der Statistik der Isomerisierung und der bevorzugt entstehenden Fragmente läßt sich zeigen, daß diese wesentlich durch stufenweise Radikalübertragung bei der Zyklisierung hervorgerufen wird. Dieser Mechanismus ist besonders häufig bei isotaktischem Polypropylen und niedriger Pyrolyse-temperatur.Auch in Polyisobutylen, [Poly(1,1-dimethyläthylen)], und Poly(1-buten), [Poly(1-äthyläthylen)], kann eine primäre statistische Spaltung aus der Fragmentverteilung bestimmt werden. Die Spaltungshäufigkeiten haben denselben Zahlenwert wie bei Polypropylen. Als wesentlich fur die Stabilisierung der Bruchstiicke beim thermischen Abbau von Vinylpolymeren wurde die Verfiigbarkeit von Wasserstoff fur intramolekulare Zyklisie-rung erkannt. Der Mangel an disponiblem Wasserstoff fuhrt bei Polyisobutylen zu der bekannten hohen Monomerausbeute, obwohl auch Fragmente bis zu den Octameren nachgewiesen werden konnten.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/macp.1975.021760714
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    Un nouveau monomère fonctionnel: le vinyl-4 dithiobenzoate de méthyle (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2143-2146 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760720
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    On the nature of “red” potassium solutions in benzene, obtained in the presence of poly(ethylene oxide)Presented at the VI. National Conference on Spectroscopy with International Participation, Slanchev Bryag (Bulgaria)1. (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 815-820 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760327
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  • 183
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    International union of pure and applied chemistry (IUPAC) (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 829-829 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760330
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  • 184
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    Über poly(1,3,5-triazin)e und poly(1,2,4-triazin)e (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 849-858 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Low molecular weight and polymeric 1,2,4-triazines were prepared in high yields by polycyclocondensation reaction of terephthalamidrazone with 1,2-diketones. The polycyclocondensation reaction of amidines like terephthalamidine with carbaldehydes yields low molecular weight and polymeric 1,3,5-triazines. Thermal analyses of poly(1,2,4-triazine)s and poly(1,3,5-triazine)s as well as pyrolytic mass spectra of the compounds were carried out.
    Notes: Durch Polycyclokondensation von Terephthalamidrazon mit 1,2-Diketonen wurden in hohen Ausbeuten niedermolekulare und polymere 1,2,4-Triazine dargestellt. Die Umsetzung von Amidinen wie Terephthalamidin mit Aldehyden ergab in einer Polycyclokondensation niedermolekulare und polymere 1,3,5-Triazine. Thermische Analysen der Poly(1,2,4-triazin)e und der Poly(1,3,5-triazin)e wurden durchgeführt und die Pyrolysemassenspektren dieser Verbindungen aufgenommen.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760402
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  • 185
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    Polymerizability of methyl substituted 1,3-dioxolanes (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 859-872 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von 4-Methyl-, 4,4-Dimethyl-, cis- und trans-4,5-Dimethyl-1,3-dioxolanen mit Bortrifluoridätherat und mit dem binären Katalysator Perchlorsäure und Acetanhydrid wurde untersucht. Bei der Polymerisation von 4-Methyl-1,3-dioxolan (1) handelt es sich um ein Gleichgewicht zwischen Monomer und Polymer. Das Polymer ist aus alternierenden Oxypropylen- und Oxymethylen-Einheiten aufgebaut. Aus der Temperaturabhängigkeit der Gleichgewichtskonzentration des Monomeren wurden die thermodynamischen Daten für die Polymerisation im Temperaturbereich von -20° bis 5°C bestimmt: ΔH1c = -3,2±0,2kcal/mol-1 und ΔS01c = -12,7±0,8 cal mol-1 K-1. Die Dimethyldioxolane polymerisieren kaum: nur aus cis-4,5-Dimethyl-1,3-dioxolan konnte eine geringe Ausbeute von flüssigem Oligomer erzielt werden; weder das trans-Isomere noch das 4,4-Dimethyl-1,3-dioxolan bildeten bei Temperaturen oberhalb -78°C Polymere oder Oligomere. Der Einfluß von Methyl-Substituenten auf die kationische Polymerisierbarkeit von 1,3-Dioxolanen wird vom thermodynamischen Standpunkt aus diskutiert.
    Notes: The polymerization of 4-methyl-, 4,4-dimethyl-, cis-4,5-dimethyl-, and trans-4,5-dimethyl-1,3-dioxolanes was investigated with boron trifluoride etherate and the perchloric acid-acetic anhydride binary system as initiators. The polymerization of 4-methyl-1,3-dioxolane (1) involves an equilibrium between monomer and polymer, and the polymer consists of alternating oxypropylene and oxymethylene units. The thermodynamic parameters for the polymerization were determined from the temperature dependence of the equilibrium monomer concentrations in the temperature range from -20 to 5°C: ΔH1c = -3,2±0,2kcal/mol and ΔS01c = -12,7±0,8 cal mol-1 K-1. Dimethyl substituted 1,3-dioxolanes are very reluctant to polymerize: only a liquid oligomer was obtained in poor yield from cis-4,5-dimethyl-1,3-dioxolane, and neither polymer nor oligomer was produced from 4,4-dimethyl- and trans-4,5-dimethyl-1,3-dioxolanes at temperatures above -;78°C. The effect of methyl substituents on the cationic polymerizability of 1,3-dioxolanes is discussed from the thermodynamic point of view.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760403
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  • 186
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    Permanganate-malic acid redox pair as the initiating system in the homogeneous polymerization of acrylamide (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2203-2223 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die durch das neue Redoxpaar Permanganat/Äpfelsäure ausgelöste homogene Polymerisation von Acrylamid in Wasser und unter Stickstoff wurde bei 35±0,2°C untersucht. Über einen großen Konzentrationsbereich der Äpfelsäure (des Aktivators) (4) von 2,5 bis 30,0 mmol dm-3 bleibt die Polymerisationsgeschwindigkeit unbeeinflußt. Zugefügte Schwefelsäure, 0,1 bis 5 mmol dm-3, erhöht die Geschwindigkeit, vermindert aber den maximalen Umsatz. Der Katalysatorexponent 0,53 bestätigt einen bimolekularen Abbruchmechanismus. Die Geschwindigkeit ist einer nicht zu hohen Monomerkonzentration proportional. Mit zunehmender Temperatur wachsen Anfangsgeschwindigkeit und Umsatz. Die gesamte Aktivierungsenergie beträgt im Bereich von 25 bis 50°C 82,20 kJ/mol (19,74 kcal/mol). Fügt man Neutralsalze, mit Wasser mischbare, organische Lösungsmittel oder Äthylendiamintetraessigsäure zu, so werden sowohl der höchste Umsatz als auch die Polymerisationsgeschwindigkeit herabgesetzt. Gibt man in Zwischenstadien der Reaktion mehr Katalysator oder auch Mangansulfat zu, dann werden Anfangsgeschwindigkeit und Umsatz erhöht. Natriumfluorid steigert die Geschwindigkeit, aber vermindert den höchsten Umsatz.
    Notes: The homogeneous polymerization of acrylamide initiated by the new redox system permanganate-malic acid was investigated in aqueous media under nitrogen at 35±0,2°C. Over a wide range of concentration (2,5 to 30 mmol dm-3) of the activator (malic acid), (4), the polymerization rate remains unaffected. Addition of sulfuric acid (0,1 to 5 mmol dm-3) increases the rate but decreases the maximum conversion. The value 0,53 of the catalyst exponent confirms a bimolecular termination mechanism. The variation of the rate at a low monomer concentration is linear. The initial rate and the conversion increase with increasing temperature. The activation energy is found to be 82,20 kJ/mol (19,74 kcal/mol) in the temperature range of 25 to 50°C. Neutral salts, water miscible organic solvents, and ethylenediaminetetraacetic acid all suppress both the limiting conversion and the rate of polymerization. The addition of more catalyst at intermediate stages as well as the addition of MnSO4 raise the initial rate and the conversion. Sodium fluoride enhances the rate but lowers the limiting conversion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760804
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  • 187
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    Polymerization of methyl methacrylate in the presence of poly(α-amino acid)s (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 629-641 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Methylmethacrylat (MMA) wurde in Gegenwart von Poly-(α-aminosäuren), Wasser und Cu(II)-Ionen untersucht. Es wurde gefunden, daß das Polymerisationsverhalten sehr stark von der Konformation der Poly(α-aminosäure) im System abhängt. Wenn die Poly(α-aminosäure) eine α-Helix-Konformation hatte, fand die Polymerisation von MMA nicht statt. Es wird vermutet, daß dies auf die Stabilität der intramolekularen Wasserstoffbrücken-Bindung in der α-Helix zurückgeführt werden muß, die zu stark ist, um einen Chelat-Komplex zwischen Kupferion, dem Polypeptid, dem MMA-Monomer und Wasser zu bilden. Wenn jedoch dieselben Polypeptide die Konformation des statistischen Knäuels einnahmen, fand die Polymerisation in geringem Ausmaß statt. Außerdem, wenn das Polypeptid mit der β-Konformation verwendet wurde, fand die Polymerisation von MMA in höherem Ausmaß statt als im Falle der Polypeptide mit der Konformation des statistischen Knäuels. Daraus wurde geschlossen, daß der Übergang der Elektronen vom Kupferion zu den Nachbaratomen eine wichtige Rolle bei der Initiierung der Polymerisation von MMA spielt.Außerdem wurde gefunden, daß die Länge der unpolaren Seitenkette des initiierenden Polypeptids die Polymerisation von MMA beeinflußt. Da die Polymerisation in Wasser durchgeführt wird, spielen die hydrophoben Bindungen zwischen der unpolaren Seitenkette des Polypeptids und dem MMA-Monomer ebenfak eine wichtige Rolle.
    Notes: The polymerization of methyl methacrylate (MMA) was studied in the presence of poly(α-amino acid)s, water, and copper(II) ion. It was found that the polymerization behaviour depends very much on the conformation of the poly(α-amino acid) in the system. If the poly(α-amino acid) had the α-helix conformation, the polymerization of MMA did not occur. This is supposed to be due to the stability of the intramolecular hydrogen bond in the α-helix, which is too high to form a chelate complex between the copper ion and the polypeptide together with the MMA monomer and water. When the same polypeptides took a random coil conformation, however, the polymerization occurred, although to a small extent. Furthermore, when the polypeptide with the β-conformation was used, the polymerization of MMA occured to a higher extent than in the case of the polypeptide with the random coil conformation. Therefore, it was concluded that the delocalization of electrons in the copper ion to the neighbouring atoms plays an important rǒle in the initiation of the polymerization of MMA.It was also found that the size of the nonpolar side chain of the initiating polypeptides affects the polymerization of MMA. Since this polymerization is carried out in water, the hydrophobic bonds between the nonpolar side chain of the polypeptide and the MMA monomer may also play an important rǒle.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760308
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  • 188
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    Gelchromatographie, 1211. Mitteilung: cf.1.. Gelchromatographisches Verhalten von Polyvinylalkoholgelen (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 657-676 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Hydrolysis of copolymers from vinyl acetate and 1,4-bis(vinyloxy)butane results in crosslinked poly(vinyl alcohol) gels. Their applicability as hydrophilic stationary phase in gel permeation chromatography is investigated using dextranes, poly(ethylene oxide)s and proteins as test materials. The gels are pressure- and biostable and show no disturbing adsorption. Depending on the conditions of synthesis, exclusion molecular weights up to 106 are obtained.
    Notes: Durch Hydrolyse von Copolymeren aus Vinylacetat und 1,4-Bis(vinyloxy)butan werden vernetzte Polyvinylalkoholgele hergestellt und ihre Eignung als hydrophile stationäre Phase bei gelchromatographischen Trennungen mit Dextranen, Poly(äthylenoxid)en und Proteinen als Testsubstanzen geprüft. Die Gele sind druck- und biostabil und zeigen keine störende Adsorption. Je nach Herstellungsbedingungen werden Ausschlußmolekulargewichte bis zu 106 erzielt.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760310
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  • 189
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    NMR-Untersuchungen an Polyacetalen, 32. Mitteilung: cf.5.. Sequenzanalyse bei 1,3,5-Trioxan/1,3-Dioxolan-Copolymeren durch 13C-NMR-Spektroskopie (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 677-689 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 1H-NMR spectra of 1,3,5-trioxane/1,3-dioxolane-copolymers show triad sequences for the methylene oxide units, whereas no sequence dependence is observed for the ethylene oxide units. In 13C-NMR-spectra, pentad sequences are observed for methylene oxide as well as for ethylene oxide units. Low concentrations of shift reagent (Eu(fod)3) in the NMR samples allow the identification of all pentad sequences; higher concentrations of Eu(fod)3 cause a splitting of signals for both units in heptad sequences.
    Notes: 1H-NMR-Spektren von 1,3,5-Trioxan/1,3-Dioxolan-Copolymeren zeigen für die Methylenoxidbausteine Triadensequenzen an, während für die Äthylenoxidbausteine praktisch keine Sequenzabhängigkeit beobachtet wird. In 13C-NMR-Spektren werden sowohl für die Methylenoxid- als auch für die Äthylenoxidbausteine Pentadensequenzen gefunden. Niedrige Konzentrationen an Verschiebungsreagenz (Eu(fod)3) in den NMR-Proben ermöglichen die Identifizierung aller Pentadensequenzen, höhere Konzentrationen an Eu(fod)3 bewirken für beide Grundbausteine eine Aufspaltung der Signale in Heptadensequenzen.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760311
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  • 190
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    Untersuchungen über Poly(arylenvinylen)e, 98. Mitt. s. Zit.1.. Zusammenhang zwischen der chemischen Struktur und der photoelektrischen Empfindlichkeit von Polyxylylidenen (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 691-698 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In a series of differently substituted and isomeric poly(arylenevinylene)s (polyxylylidenes) it was found, that with the undoped polymers there is the relation (1) between the optical excitation energy Eopt and the photoelectrical sensitivity JPh. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {J_{{\rm Ph}} = A(T)\exp - (0,34E_{{\rm opt}} /kT);} & {T = {\rm Const}{\rm .}} & {(1)} \\ \end{array}$$\end{document} This relation is discussed on the basis of a photochemical ionization of the macromolecules.
    Notes: An einer Reihe verschieden substituierter und isomerer Poly(arylenvinylen)e (Polyxylylidene) wurde gefunden, daß bei den undotierten Polymeren zwischen der optischen Anregungsenergie Eopt und der photoelektrischen Empfindlichkeit JPh der Zusammenhang (1) besteht. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {J_{{\rm Ph}} = A(T)\exp - (0,34E_{{\rm opt}} /kT);} & {T = {\rm Const}{\rm .}} & {(1)} \\ \end{array}$$\end{document} Diese Beziehung wird auf der Grundlage einer photochemischen Ionisation der Makromoleküle diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760312
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  • 191
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    Sequence distribution of components and stereoregularity in methyl methacrylate/methyl acrylate copolymers determined by proton nuclear magnetic resonance spectroscopy (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 699-708 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 1H-NMR-Spektren von Methylmethacrylat/Methylacrylat-Copolymeren, die mit radikalischen und mit anionischen Initiatoren hergestellt waren, wurden auf die Sequenzabfolge der Grundbausteine und auf die Stereoregularität hin untersucht. Regeln für die chemische Verschiebung innerhalb Methylmethacrylat-zentrierter Triaden wurden abgeleitet.
    Notes: 1H-NMR spectra of methyl methacrylate/methyl acrylate copolymers obtained with radical and anionic initiators were analyzed in terms of sequence distribution of components and stereoregularity. Some rules related to the chemical shifts in triads centered with methyl methacrylate units were derived.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760313
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  • 192
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    Functional monomers and polymers, 24Part 23: M. Miyata, K. Takemoto, J. Polym. Sci., Polym. Lett. Ed., 13, 221 (1975).. Emission spectra of polymers containing nucleic acid bases (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2683-2699 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Emissions- und die UV-Spektren von monomeren und dimeren Modellverbindungen und von Polymeren, die Adenin-, 6-(Methylamino)purin-oder 6-(Dimethylamino)purin-Gruppen enthalten, wurden bei 77 K in Wasser/Äthylenglykol oder Äthanol vermessen. Es konnten so Informationen über den Charakter und die Stärke der zwischen den Nukleinbasen herrschenden Wechselwirkungen erhalten werden. Die Emissionsspektren der Dimeren und Polymeren zeigen bei geeignetem Abstand der Adeninringe starke Wechselwirkungen und die Bildung von Excimeren an. Allerdings wurden in Äthanol oder in Wasser/Äthylenglykol-Mischungen bei pH=2 keine Excimeremissionen mehr beobachtet. Die UV-Spektren lassen auf zwei verschiedene Arten von Wechselwirkungen zwischen den Nukleinbasen schließen, je nachdem ob diese „plane in plane“ oder koplanar angeordnet sind.
    Notes: The emission and the ultraviolet spectroscopies were studied at 77 K in water/ethylene glycol or ethanol for polymers containing adenine, 6-(methylamino)purine, and 6-(dimethylamino)purine moieties, and for the corresponding dimeric and monomeric model compounds, in order to obtain more information about the nature and extent of the interactions between nucleic acid bases in the polymer chains. The emission spectra of the dimeric compounds and the polymers suggested the formation of excimers and the existence of strong interactions between the adenine rings of suitable compounds. These excimer emissions were not observed in the spectra measured in ethanol, and in water/ethylene glycol solutions at pH 2. The ultraviolet spectra suggested two kinds of base-base interactions for plane in plane and coplanar arrangement.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760917
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  • 193
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    Characterization of the structure of the stereocomplex of poly(methyl methacrylate) in solution from NMR relaxation data (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 729-743 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit dem Impulsspektrometer bestimmte Relaxationszeiten T2, sowie Linienformen in Hochauflösungs- und Breitband-Kernresonanzspektren (HR- und BL-NMR) haben gezeigt. daß im assoziierten Stereokomplex von isotaktischem (it-) und syndiotaktischem (st-) Poly(methylmethacrylat) (PMMA) zwei Protonentypen vorkommen, die sich durch + Beweglichkeit unterscheiden. Aus der Analyse der unter dem magischen Winkel aufgenommenen Kernresonanzspektren (MAR-NMR) wurde gezeigt, daß die Beweglichkeit von Estergruppen im Stereokomplex weitgehend behindert ist. Aus der Temperaturabhängigkeit der HR-NMR Spektren der gemischten Lösungen von it- und st-PMMA in Benzol können die assoziierten Stereokomplexsegmente als Vernetzungspunkte eines Gerüstes von nichtassoziierten Sequenzen charakterisiert werden.
    Notes: From the values of relaxation times T2 determined on a pulse spectrometer, and from the shape of bands in high resolution (HR-) and broad line (BL-) NMR spectra, two types of protons, different in mobility, were found to exist in the associated stereocomplex of isotactic (it-) and syndiotactic (st-) poly(methyl methacrylate) (PMMA). From the analysis of NMR spectra, measured at magic angle rotation (MAR-NMR), the mobility of the ester groups in the stereocomplex is shown to be greatly hindered. Temperature changes of HR-NMR spectra of mixed solutions of it- and st-PMMA in benzene indicate that the associated segments of the stereocomplex can be characterized as junctions of a network of nonassociated sequences.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760315
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  • 194
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    Zur Struktur des Polybutadiens, 32. Mitteilung: cf.2.. Das 13C-NMR-Spektrum des cis-1,4-1,2-polybutadiens (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 759-765 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The 13C-NMR spectrum of a polybutadiene with cis-1,4 and 1,2-structure units is interpreted and assigned. The shift of the resonance signals of the double bond of the cis-1,4 unit caused by the neighbouring 1,2 structure units, can be calculated from a set of empirical shift parameters.
    Notes: Das 13C-NMR-Spektrum eines Polybutadiens aus cis-1,4- und 1,2-Struktureinheiten wird interpretiert und zugeordnet. Die Verschiebung der Resonanzsignale der Doppelbindung der cis-1,4-Verknüpfung als Folge benachbarter 1,2-Einheiten kann durch einen Satz empirischer Shiftparameter berechnet werden.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760317
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  • 195
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    Anwendung der Metathese-Reaktion auf die Mikrostrukturbestimmung von Polybutadienen (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 775-779 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760319
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  • 196
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    Zum Mechanismus des Abbaus von Polymeren in Lösung durch Ultraschall (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 745-757 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The degradation reaction of dextran by the action of ultrasound was investigated within the molecular weight range from 30 000 to 90 000 in different solvents. The degradation products were characterized by their molecular weight distributions obtained by chromatography on porous glass. From the results of the experiments it could be shown that degradation follows a first order reaction, that the rate constant of degradation is proportional to the molecular weight, and that the molecules break preferentially into two parts of approximately equal size. The nature of the solvent has a considerable effect on the rate constants, which could be shown to be proportional to the enthalpy of vaporization of the solvent. The effect of polymer conformation on the degradation constants was studied and it was found that the degradation constants increase with expansion of the polymer coils.The experimental results confirm the general assumption, that the cavities, which are caused by ultrasound, are responsible for the degradation reaction. It is not possible, however, to conclude from the experimental results known so far, whether the inhomogenous flow fields or the shock waves, which arise from the collapse of cavitation bubbles, are responsible for the rupture of the molecule. The experimental result, that expanded polymer coils are more easily degraded. favours the mechanism which implies shock waves. Furthermore, a model in which both effects are acting together, in the way that the inhomogeneous flow fields at first stretch the polymer coil, whereas the shock wave, which immediately follows, breaks the molecule, is suggested to explain the rupture of the molecules.
    Notes: Die Abbaureaktion von Dextran durch Ultraschall wurde im Molekulargewichtsbereich von 30 000 bis 90 000 in verschiedenen Lösungsmitteln untersucht. Die Abbauprodukte wurden durch ihre Molekulargewichtsverteilungen, die mit Hilfe von Chromatographie an porösem Glas bestimmt wurden, charakterisiert. Aus den Ergebnissen der Untersuchungen konnte abgeleitet werden, daß die Abbaureaktion nach erster Ordnung verläuft, die Abbaukonstante proportional dem Molekulargewicht ist, und die Moleküle bevorzugt in zwei nahezu gleichgroße Bruchstücke zerfallen. Die Art des Lösungsmittels hat dabei einen erheblichen Einfluß auf die Abbaukonstanten; es wurde gefunden, daß diese der molaren Verdampfungsenthalpie des Lösungsmittels direkt proportional sind. Der Einfluß der Konformation des Polymeren auf die Abbaukonstanten wurde studiert, wobei sich ergab, daß mit einer Aufweitung der Polymerknäuel die Abbaukonstanten größer wurden.Die Ergebnisse bestätigen die allgemeine Auffassung, daß die Kavitäten, die bei der Ultrabeschallung entstehen, für die Abbaureaktion verantwortlich sind. Eine eindeutige Entscheidung, ob die inhomogenen Strömungsfelder oder die Stoßwellen, die bei der Implosion der Kavitäten entstehen, für den Molekülbruch letztlich maßgebend sind, kann mit den bisher vorliegenden Ergebnissen nicht getroffen werden. Der Befund, daß aufgeweitete Knäuel leichter abgebaut werden, spricht für den Stoßwellenmechanismus. Andererseits wird ein Modell für die Abbaureaktion angegeben, in dem beide Effekte insoweit zusammenwirken, daß die inhomogenen Strömungsfelder das Polymerknäuel zunächst strecken und die nachfolgende Stoßwelle den Molekülbruch bewirkt.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760316
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  • 197
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    Viscosity and optical observation on poly(ethylene terephthalate) during annealing and thermal scanning (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 767-774 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird über einige Ergebnisse berichtet, die bei der Beobachtung von Polyäthylenterephthalat [Poly(oxyäthylenoxyterephthaloyl)] mit dem optischen Mikroskop während des isothermen Temperns und Aufheizens zwischen Zimmer- bzw. Tempertemperatur und Schmelztemperatur erhalten wurden. Parallel dazu wurden Änderungen des Molekulargewichts viskosimetrisch kontrolliert. In allen Versuchen wurden Sphärolithe beobachtet, deren Größe sich nur während der Kristallisation und im Schmelzbereich änderte. Aus den Ergebnissen wird geschlossen, daß die großen Änderungen, die das endotherme, Maximum der DSC-Kurve bei Temperaturen unterhalb der Schmelztemperatur zeigt (peak II), nur durch Änderungen der Ordnung im Innern der Sphärolithe verursacht sein können. Damit wird das von Roberts und Holdsworth vorgeschlagene Modell bestäigt.
    Notes: Some results obtained with poly(ethylene terephthalate) [poly(oxyethyleneoxyterephthaloyl)] following by optical microscopy the isothermal annealing and the thermal scanning from room temperature or annealing temperature up to the melting point are reported. Besides, the variation of the molecular weight is controlled by viscometry. It is observed that the structure is always characterized by spherulites, whose sizes change only during the crystallization and in the melting range. The conclusion is reached that the structural modifications on which the large variations of the endothermal maximum of the DSC curve below the melting temperature (peak II) depend, occur inside the spherulites. The model suggested by Roberts and Holdsworth seems to be supported by our data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760318
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  • 198
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    Electronic Resource
    Cationic polymerization of p-substituted α-methylstyrenes, 1. Tacticity by 1H- and 19F-NMR spectroscopy (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 781-787 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760320
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  • 199
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    Electronic Resource
    Infrared spectra of deuterated poly(methyl methacrylate), (—CD2C(CH3)COOCH3)n— (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 789-794 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760321
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  • 200
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    Studies on the hydrolysis reaction of model substances of cellulose in the presence of polymer catalystThe term “catalyst” is being used in the present paper in a conventional way. However, the polymers are by no means catalysts as defined earlier by Ostwald [Physik. Z. 3, 313 (1902)]. See for detailed discussion, articles in Nature 242, 605 (1973) and in J. Amer. Chem. Soc. 95, 2293 (1973)., 2Part 1: cf.1.. Effect of inorganic salts on the hydrolysis rate of dextrin catalyzed by poly(vinyl alcohol-co-vinylsulfonic acid) (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 2491-2500 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß von anorganischen Salzen auf die durch Poly(vinylalkohol-co-vinylsulfon-säure) katalysierte Hydrolyse von Dextrin wurde untersucht. Die Reaktionsgeschwindigkeit wird durch Natriumchlorid und Kaliumnitrat vergrößert und durch Natriumsulfat und Kaliumsulfat vermindert. Man kann annehmen, daß bei Anwesenheit grofier Salzmengen die H+-Ionenaktivitat fur die Hydrolyse die entscheidende Rolle spielt, denn die Reaktionsgeschwindigkeit zeigt eine lineare Abhängigkeit vom pH-Wert der Mischung und der Logarithmus der Reaktionsgeschwindigkeit ist proportional zur Ionenstarke, wenn diese größer ist als 0,5 mol. Der Unterschied in der Geschwindigkeit zwischen der durch die Copolymeren und der durch Schwefelsaure katalysierten Reaktion verschwindet bei Zusatz von Salzen unabhängig davon, ob die Reaktion langsamer oder schneller wird. Die Bestimmung der Aktivierungsparameter ergab, dafi die durch den Zusatz von Salzen erzielte Beschleunigung auf die Zunahme der Aktivierungsentropie zuruckzufuhren ist, obwohl die Aktivierungsenthalpie ebenfalls steigt. Dies unterscheidet sich deutlich von der bei Einfuhrung von Hydroxyäthyl-Einheiten in die Copolymeren beobachteten Geschwindigkeitszunahme. Die Beschleunigung beruht also in beiden Fällen auf unterschiedlichen Mechanismen, wie aus der isokinetischen Beziehung folgt.
    Notes: The effect of inorganic salts on the hydrolysis rate of dextrin catalyzed by poly(vinyl alcohol-co-vinylsulfonic acid) was studied. The reaction is enhanced by addition of sodium chloride and potassium nitrate, and retarded with sodium sulfate and potassium sulfate. It may be presumed that in the presence of large amounts of salts the acidity is a predominant factor for the hydrolysis rate of dextrin in the present system, since it was found that the rate shows a linear relationship with the pH of the reaction mixture, and that the logarithm of the reaction rate was proportional to the ionic strength at values 〉 0,5 moll-1. The difference in the reaction rates catalyzed by the copolymer or sulfuric acid was diminished with addition of salt, having no relation to whether the reaction rate was enhanced or retarded. Activation parameters of these reactions in the presence of salt were investigated, and it was found that the rate acceleration obtained by addition of salt was due to the increase in entropy of activation, although the enthalpy of activation was also increased. These effects are quite different from that observed in the rate acceleration by introducing hydroxyethyl units into the copolymer, suggesting that the reaction mechanisms for both rate acceleration effects are quite different, as can be inferred from the isokinetic relationships.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760902
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