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  • Articles: DFG German National Licenses  (20)
  • 1980-1984  (20)
  • Polymer and Materials Science  (20)
  • 1
    Electronic Resource
    Electronic Resource
    X-Ray diffraction studies on the structure of hydrated collagen (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2539-2547 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of the humidity-sensitive spacing, d, related to the lateral packing of collagen molecules was measured for fully hydrated collagen. In the vicinity of 0°C, a sudden change in d was observed, which was reversible with temperature. In the diffraction profile, below 0°C, a set of diffraction peaks identified with the hexagonal crystalline form of ice was observed. With the reduction in water content, the intensity of the set of diffraction peaks decreased and was found to be zero at a water content of 0.38 g/g collagen. These results were considered to be caused by the frozen water in collagen fibril below 0°C. According to the water content dependence of d, it was considered that up to a certain water content water absorbed would be stowed in the intermolecular space of collagen and above that water content water molecules would aggregate to make pools, i. e., extrafibrillar spaces. The unfreezable bound water was considered to be located in the intermolecular space of collagen. Size of the extrafibrillar space, determined from the intensity analysis of a smallangle x-ray scattering pattern, corroborates the speculation that the water showed in the extrafibrillar space is freezable and free. The formation of the hexagonal crystalline form of ice in the extrafibrillar space was considered to cause the sudden change in d at 0°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360221208
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  • 2
    Electronic Resource
    Electronic Resource
    Limiting viscosity number and sedimentation coefficient of solutions of cellulose acetates (1982)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 3075-3087 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscosity and sedimentation experiments were made for fractions of cellulose acetate CA (degree of substitution, D.S. = 2,46) in acetone and CA (D.S. = 2,92) in N,N-dimethylacetamide (DMAc) at 25°C. The following empirical relations were established between the sedimentation coefficient at infinite dilution s0 and the weight average molecular weight M̄w: s0 = 1,02 · 10-14 M̄w0,39 (s) for CA (D.S. = 2,46) in acetone and s0 = 1,83 · 10-14 M̄0,24w (s) for CA (D.S. = 2,92) in DMAc. From the analysis of the molecular weight dependence of s0 and the limiting viscosity number [η] (method 1B) and the concentration-dependence parameter ks and [η] (method 1E), the solvent draining parameter X was estimated to be less than 1, indicating that the free draining effect cannot be ignored. The unperturbed chain dimension parameter A was determined from data on s0 and M̄w to be between 1,72 · 10-8 and 1,80 · 10-8 cm for CA (D.S. = 2,46) in acetone and between 1,63 · 10-8 and 1,68 · 10-8 cm for CA (D.S. = 2,92) in DMAc. These values are in good agreement with those estimated by thermodynamic and viscometric approaches.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1982.021831220
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  • 3
    Electronic Resource
    Electronic Resource
    Stereoselective solvolyses of amino acid p-nitrophenyl esters by optically active imidazole-containing polymers (1982)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 2041-2046 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolytic reactions of N-methoxycarbonyl-D- and L-phenylalanine p-nitrophenyl ester (D-2 and L-2) by poly(N-methacryloyl-L-histidine) and poly(N-methacryloyl-L-histidine methyl ester) were carried out. However, no significant difference between the solvolytic rates of the two enantiomeric substrates was observed. To investigate the effect of hydrophobic interaction, N-acetyl-, N-pentanoyl- and N-octanoyl-L-histidine were prepared and their effect on the ester solvolyses was studied. The rates were generally enhanced as the alkanoyl group became larger. Furthermore N-octanoyl-L-histidine showed some degree of stereoselective catalysis. Accordingly, when polymers with increased hydrophobicity were prepared by copolymerizing N-methacryloyl-L-histidine and its methyl ester with dodecyl methacrylate and were subjected to catalyze the solvolyses of optically active esters, the apparent catalytic rate constant for L-2 was observed to be 1,3 times larger than that for the D-2. The enantio-selectivity became more pronounced as the hydrophobic character of polymer catalysts was enhanced.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1982.021830901
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  • 4
    Electronic Resource
    Electronic Resource
    Role of hydrophobic interaction in the enantioselective solvolyses of amino acid p-nitrophenyl esters by optically active imidazole-containing polymers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 147-152 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolytic reactions of N-benzyloxycarbonyl-D-phenylalanine p-nitrophenyl ester and N-benzyloxycarbonyl-L-phenylalanine p-nitrophenyl ester by optically active imidazole-containing polymers were performed at different temperatures and in aq. ethanol of different water contents. The catalyst polymers employed were homopolymers of N-methacryloyl-L-histidine (1a) and N-methacryloyl-L-histidine methyl ester (1b), as well as copolymers of 1a with dodecyl methacrylate (DMA) and 1b with DMA. In 30 vol. -% aqueous ethanol at pH 7,02 the homopolymers did not show any enantioselective catalysis. However, the copolymers did exhibit enantioselective catalysis, viz., kcat(L)/kcat(D) = 1,25 for poly (1b-co-DMA) containing 5,7 mol-% of DMA. As the reaction temperature was lowered, the reaction rate increased and the enantioselectivity was enhanced (kcat(L)/kcat(D) = 1,67 for poly (1b-co-DMA) at 10°C). When the ethanol content was decreased, enhanced reaction rates and enantioselectivity (kcat(L)/kcat(D) = 1,65 for poly (1 b-co-DMA) in 20 vol.-% aqueous ethanol) were observed. From these results it is concluded that hydrophobic interaction plays an important role in the enantioselective catalysis of optically active imidazole-containing polymers.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840115
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of ψ(+) and ψ(-) DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 325-335 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: DNA molecules can be organized into ordered aggregates of opposite handedness by complexation with polylysine and other polypeptides; we have investigated the conditions under which ψ(+) and ψ(-) structures are produced with double-helical synthetic polynucleotides. Both poly(dGdC)·poly(dGdC) and poly(dAdT)·poly(dAdT) readily form ψ(-) structures with polylysine, although the method of preparation can alter the CD spectra. The GC copolymer, which is more susceptible to conversion into A or Z conformers, forms ψ(+) structures with lysine-alanine copolypeptides more readily than the AT copolymer. Nucleotide base modifications that favor the Z structure, such as bromination and methylation, also favor ψ(+) formation, and the Co(NH3)6Cl3 reagent that readily induces the Z structure also leads to ψ(+). Thus, the production of the ψ(+) structure seems to be frequently correlated with susceptibility to A or Z formation, although there are some cases in which the B conformer also leads to ψ(+). Polyethylene glycol generally produces a ψ(-) structure; the differentiation between ψ(+) and ψ(-) structures seems to require electrically charged polymers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230211
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  • 6
    Electronic Resource
    Electronic Resource
    Rates of structural fluctuations of lysozyme in the range of thermal unfolding transition (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1691-1705 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrogen-deuterium exchange reaction for the tryptophan residues in lysozyme have been followed in 4.5M LiBr at pH 7.2 in the temperature range of the unfolding transition by measuring the transmittance change at 293 nm. The exchange reaction proceeded in three phases at low temperature for native protein. The first and the second phases were ascribed to the H-D exchange reactions of three relatively exposed tryptophan residues on the molecular surface. The third phase corresponded to the H-D exchange reaction of the three tryptophan residues buried in the interior of the molecule. The H-D exchange reaction proceeded in two phases near the melting temperature and in a single phase at high temperature, where almost all molecules are unfolded. The H-D exchange of three tryptophan residues buried in folded molecules was caused by fluctuation between the folded and unfolded structure of the protein molecule. The rates of such a fluctuation were determined from the rates of the exchange reaction at various temperatures. These rates agreed very well with those determined from the temperature-jump method. This means that a protein molecule in solution fluctuates between the N- and D-states at every temperature within the transition region, where the N-form is the tightly folded native structure and the D-form the randomly coiled chain. From measurements of thermal unfolding of ester-108-lysozyme and the binding constant of (NAG)3 to ester-108-lysozyme, it was found that almost all cross-linked molecules are in the folded state near 50°C and pH 7.2 in 4.5M LiBr, where intact molecules are unfolded. We also studied the H-D exchange reaction of ester-108-lysozyme. In the temperature region of 43-50°C, about 70% of the exchangeable tryptophan residues of ester-108-lysozyme were exchanged within 1 s immediately after the mixing of D2O, in spite of the fact that almost all molecules are in the folded state. This was considered the premelting of the surface of a corss-linked molecule.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200810
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  • 7
    Electronic Resource
    Electronic Resource
    Induction of helicity in polyuridylic acid and polyinosinic acid by silver ions (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 539-556 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silver ions binding to poly(U) and poly(I) produce highly ordered multistranded helices under conditions which would otherwise lead to random coils. Evidence for helicity comes from the hypochromicity and high ellipticity generated in the polymers by Ag+ binding, as well as from x-ray studies and from the cooperativity of the Ag+ complexing reaction. Continuous variation studies show that both polymers form 1:1 and 2:1 polymer-Ag+ complexes. Low pH favors the 1:1 complex with poly(U) and the 2:1 complex with poly(I); the reverse is true at high pH. Ag+ binding and proton-release experiments make it clear that at low pH, unprotonated electron-donor groups are complexed preferentially, but that at high pH, Ag+ readily displaces H+ from protonated groups. In poly(I) the unprotonated donor is N(7), leading at low pH to a 2:1 complex containing N(7)-Ag-N(7) bonds; at high pH, proton release from N(1) leads to a 1:1 complex containing N(1)-Ag-O bonds. In poly(U) there is no unprotonated donor; the low-pH 1:1 complex involves deprotonation of only one N(3) per bound Ag+, leading to N3-Ag-O bonding, while high pH causes deprotonation of two N(3) per Ag+ and a 2:1 N(3)-Ag-N(3) complex. Thus silver ions react with the nucleotide bases in chemically predictable ways, and the formation of different Ag-nucleotide bonds leads to different multiple-helix structures.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360190308
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  • 8
    Electronic Resource
    Electronic Resource
    Photoinduced acrylamide graft polymerization onto extended hard elastic polypropylene (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 637-643 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hard elastic PP films were graft polymerized with PAAm, using a photoinduction method derived by Tazuke. The graft yield (GY) was measured as a function of extension applied to the PP film during the polymerization. The GY increased stepwise when the extension increased above the yield point. This remarkable increase in GY is due to the fact that the surface of voids created by extension are involved in the graft polymerization. The GY obtained under extensions larger than the yield point was much larger than that ever achieved for the usual PP films. The residual strain after the graft polymerization increased with increase in GY, and the relationship between them changed at about 40% GY, suggesting that some change occurred in the location of grafted PAAm in PP films. The graft ratio, determined after complete extraction of PP and PAAm homopolymers, remained nearly constant with polymerization time, except at the early stage of the polymerization. The effect of extension on the graft ratio implied that the size of the voids may affect the degree of polymerization of graft PAAm when the size is comparatively small.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070270226
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  • 9
    Electronic Resource
    Electronic Resource
    Polymerization of N-vinylcarbazole in the presence of magnetic ferric oxide particlesCorrected proofs received September 21, 1984 (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 4461-4463 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291280
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  • 10
    Electronic Resource
    Electronic Resource
    Photopolymerization of methyl methacrylate initiated by a nitrogen ylide (1984)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 126 (1984), S. 19-26 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde die Sensibilisierung der Photopolymerisation durch 1-Ethoxycarbonyliminopyridiniumylid (IPYY) untersucht. Nur Acrylmonomere wie Methylmethacrylat und Methylacrylat konnten durch IPYY photoinitiiert werden, Styrol wurde durch den verwendeten Initiator nicht angeregt. Durch kinetische Untersuchungen, die inhibierende Wirkung von Benzochinon und durch die Copolymerisation mit Styrol wurde ein Radikalmechanismus bestätigt. Die kinetischen Daten weisen auf eine Komplexbildung zwischen IPYY und dem Monomerbaustein hin, die ein Initiatorradikal erzeugt.
    Notes: The sensitization effect of 1-ethoxycarbonyliminopyridinium ylide (IPYY) on the photopolymerization was studied. Only acrylic monomers such as methyl methacrylate and methyl acrylate could be photoinitiated by IPYY, styrene being unaffected by the initiator employed. A free radical mechanism was confirmed by the kinetic study, the inhibiting effect of benzoquinone and the copolymer composition with styrene. Kinetic data suggested the formation of a complex between the IPYY and each monomer, which generates an initiating radical.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1984.051260103
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