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  • Polymer and Materials Science  (18)
  • Physics  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Kinetic determination of stereoselectivity in the anionic polymerization of α-ethyl-α-phenyl-β-propiolactone (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 811-819 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the anionic polymerization of optically active α-ethyl-α-phenyl-β-propiolactone (optical purity 16,8%) initiated with bis(triphenylphosphine)iminium acetate was investigated and the rate constants for the homo-(kph) and crosspropagation (kpc) (considering R and S enantiomers as comonomers) were determined. The knowledge of the values of kph and kpc, equal to 1,53·10-4 and 9,0·10-51· mol-1·s-1, respectively (25°C, CH2Cl2 solvent), allowed us to calculate the distribution of homosequences in the polymer prepared from racemic monomer. The concentration of homosequences was slightly higher than calculated for the process with random enchainment of enantiomers. Thus, the content of homodyads, homotriads, and homotetrads equals 63, 40, and 25%, whereas for the random process it was 50, 25, and 13%, respectively. This difference is, however, too small to create homoblocks which could be responsible for the observed crystallinity of these polymers.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840415
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  • 2
    Electronic Resource
    Electronic Resource
    Structure of active species in the cationic polymerization of β-propiolactone and ε-caprolactone (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 655-667 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The study of the structure of the end-groups of poly(β-propiolactone) and poly(ε-caprolactone) by 1H, 31P{1H} NMR, and IR spectroscopy revealed that the mode of ring scission in the monomer in the first propagation step depends on the initiator used. In the initiation of the β-propiolactone and ε-caprolactone polymerization with halonium salts ((CH3)2Br⊕SbF6⊖ or (CH3)2I⊕SbF6F6⊖) the exocyclic oxygen atoms in the monomer molecules are attacked and oxonium ions are formed. The propagation steps proceed with alkyl-oxygen bond scission in the active center and with attack at the exocyclic oxygen atom in the subsequent monomer molecule. Thus, the tertiary oxonium ions are the exclusive active species from the very beginning of the polymerization. Acylium cations (CH3CO⊕ SbF6⊖ or CH3CH2CO⊕SbF6⊖) as initiators attack both exo-and endocyclic oxygen atoms in the monomers and the initiation proceeds with almost equal proportions of alkyl-oxygen and acyl-oxygen bond scission. Thus, in the polymerization of β-propiolactone the concentration of the acylium growing species decreases with increasing number of propagation steps and finally the tertiary oxonium ions are becoming the exclusive growing species. In the polymerization of ε-caprolactone the active acylium centers apart from propagation participate also in side reactions leading to the cleavage of a proton.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021850405
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  • 3
    Electronic Resource
    Electronic Resource
    Formation of the intermediate cyclic six-membered oxonium ion in the cationic polymerization of β-propiolactone initiated with CH3CO⊕SbF⊖6 (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2283-2290 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Analysis of the 1H NMR spectra of \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document} /β-propiolactone and of the model systems \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document}/(CH3)2O and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} \mathop {\rm C}\limits^ \oplus {\rm OSbF}_{\rm 6}^ \ominus $\end{document}/CH3COOCH3 in liquid SO2 in the temperature region -70 to -20°C revealed that the reaction of the acetylium cation with β-propiolactone leads to the cyclic six-membered oxonium ion 4, participating as an intermediate in the initial stage of polymerization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861109
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  • 4
    Electronic Resource
    Electronic Resource
    Telechelic poly(ε-caprolactone) terminated at both ends with OH groups and its derivatization (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 1457-1465 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of highly uniform (1,08 ≤ Mw/Mn ≤ 1,13) telechelic poly(ε-caprolactone) terminated at both ends with OH groups and its derivatization leading to poly(ε-caprolactone) with pyrene end-groups are described. The synthesis, carried out in THF at room temperature, involves initiation with (CH3CH2)2AlO(CH2CH2O)3Al(CH2CH3)2, leading to poly(ε-caprolactone) macromolecules growing at both ends. The active centers were deactivated with acetic acid, giving macromolecules with OH end-groups. Reaction of α,ω-dihydroxypoly(ε-caprolactone), HO-poly(εCL)-OH, with 4-(1-pyrenyl)butyryl chloride yields α,ω-di-1-pyrenylpoly(ε-caprolactone), Py-poly(εCL)-Py. Polymers are characterized by GPC, 1H NMR, and UV spectroscopies. The UV spectra of polymers with pyrene end-groups are compared with the UV spectra of the model compound.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920701
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  • 5
    Electronic Resource
    Electronic Resource
    Structure of active centers and mechanism of anionic and cationic polymerization of δ-valerolactone (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2027-2040 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The determination of the structure of the end groups in poly(δ-valerolactone) (poly(δVL)) by using 1H, 31P NMR, and IR spectroscopy showed that in the cationic polymerization of δVL, propagation proceeds via cyclic dialkoxycarbenium ions as active species and the monomer molecules are incorporated into the polyester chains by an alkyl-oxygen bond scission. In the anionic polymerization of δVL, propagation proceeds via alcoholate anions and monomer molecules are added with breaking the acyl-oxygen bond. A similar cationic mechanism operates with alkylating ((CH3)2I⊕SbF6⊖) and acylating (CH3CO⊕SbF6⊖) initiators. However, with the latter, the cyclic dialkoxycarbenium active centers coexist with the acylium cations during the initial period of polymerization. Finally, however, the cyclic dialkoxycarbenium ions become the only active species. The mechanisms of ionic propagation in the polymerization of β-propiolactone, δ-valerolactone, and ε-caprolactone are compared.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880902
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetically controlled formation of macrocyclic oligomers in the ring-opening polymerization (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1469-1482 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic schemes are solved for polymerization systems involving competition between linear growth and cyclisation by back-biting to an optional chain unit and/or to the last unit (end-to-end ring closure). A fast reaction of a growing centre with an end group may lead to a situation, called here “kinetic enhancement in macrorings”, in which the transient concentration of cyclics formed in polymerization system exceeds their equilibrium concentration. Sometimes, a peculiar kinetics may be observed in which propagation proceeds on linear active macromolecules, but the polymerization leads almost exclusively to the cyclic products. On the other hand, fast propagation due to a high reactivity of monomer may lead to kinetic reduction of macrorings. Several situations are considered with examples taken from cationic polymerization of cyclic acetals and siloxanes (kinetic enhancement) or anionic polymerization of ∊-caprolactone (kinetic reduction). Kinetic schemes are numerically solved by computer for some arbitrarily assumed rate constants. This is the first paper of a series aiming to relate the kinetically controlled concentration of macrorings to the polymerization mechanism and the numerical values of the rate constants.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810710
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  • 7
    Electronic Resource
    Electronic Resource
    Kinetics of ∊-caprolactone polymerization and formation of cyclic oligomersDedicated to Prof. H.-J. Cantow on his 60th birthday (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2159-2171 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the anionic polymerization of ∊-caprolactone, including the kinetics of macrocyclization and the kinetics of macrocycles propagation in THF solution, initiated with (CH3)3SiONa, were investigated. Rate constants of propagation (kp(n)) and of back-biting (kd(n)) involving monomer and cyclic oligomers (macrocycles) with n = 2, 3, … monomeric units were determined for n ≤ 7. It was found that starting from the tetramer kd(n) ∼ n-1,4±0,1 and kp(n) ∼ n0,7±0,15 (in Jacobson-Stockmayer's theory kp(n) ∼ n). This discrepancy is explained in terms of “conformational hindrance”, increasing for small cycles with the increase of the ring size until a certain ring size is reached. This hindrance decreases the availability of some of the ester groups in the macrocyclics for attack of the growing species, lowering in this way the exponent in the dependence of kp(n) on n from one to a lower value.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021841020
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  • 8
    Electronic Resource
    Electronic Resource
    Ring-opening polymerization with kinetically controlled enhancement of macrocyclic oligomers or linear macromolecules (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2581-2594 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The equilibrium and the kinetics of the ring-opening polymerization accompanied with backbiting and end-to-end ring closure are analyzed using computer simulation. The influence of monomer ring strain and competition between back-biting and end-biting on the overall kinetic process is evaluated. The results of calculations are compared with examples from the ionic ring opening polymerization of heterocyclic monomers. It is established that in the polymerization of nonstrained monomers fast end-biting manifests itself by an induction period. In the absence of end-biting the polymerization of strained monomers yields a system in which the polymer concentration is temporarily higher than at equilibrium (kinetic enhancement in polymer). On the other hand, very fast end-biting, hindered only in the case of the monomeric species by the ring strain, results in concentrations of the macrocyclics which are transitorily higher than the corresponding equilibrium concentrations (kinetic enhancement of macrocycles). The polymer synthesis with kinetically controlled concentration of cyclics is indicated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861219
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics of the anionic polymerization of ∊-caprolactone with K+ · (dibenzo-18-crown-6 ether) counterion. Propagation via macroions and macroion pairsDedicated to Prof. Teiji Tsuruta on the occasion of his 70th birthday (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 735-744 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Following our earlier work on the polymerization of lactones involving crowned cations, kinetics of the anionic polymerization of ∊-caprolactone (∊CL) with K+ · (dibenzo-18-crown-6 ether) (K+DB18C6) counterion was studied calorimetrically in THF solution in the temperature range from 0 to 20°C. Dissociation constants of CH3(CH2)5O-K+DB18C6, modelling the active centers, were determined conductometrically: KD (20°C) = 7,7 · 10-5 mol · dm-3, ΔH0D = 9,3 ± 0,2 kJ · mol-1, ΔS0D = -47 ± 2J · mol-1 · K-1. From kinetic measurements and from measurements of the dissociation constant of CH3(CH2)5O- K+DB18C6, rate constants of propagation via macroions and via macroion pairs were determined. Activation parameters for propagation via these species are equal to: ΔH≠(±) = 39,2 ± 0,2 kJ · mol-1, ΔS≠(-) = -63 ± 1 J · mol-1 · K-1, ΔH≠(±) = 13,7 ± 0,1 kJ · mol-1, ΔS≠(±) = -185 ± 2 J · mol-1 · K-1. At 20°C, kp- = 3,50 · 102 dm3 · mol-1 · s-1 and kp± = 5,2 dm3 · mol-1 · s-1. Due to the large difference of ΔH≠ for propagation via macroions and macroion pairs (vide supra), the isokinetic point (kp- = k±p) would appear at -65°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920323
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of proteins with polymeric latexes (1995)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 6 (1995), S. 526-533 
    Details
    ISSN: 1042-7147
    Keywords: polyacrolein containing latexes ; protein adsorption ; protein immobilization ; human serum albumin ; human gamma globulins ; horseradish peroxidose ; bioactivity of proteins attached to latexes ; 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
    Notes: Syntheses, modifications and properties of latexes containing polyacrolein, suitable for the covalent immobilization of proteins, are described. Results of the studies of physical adsorption and covalent attachment of human serum albumin and gamma globulins are discussed. Procedures allowing immobilization of the enzyme, horseradish peroxidase, are described. Changes in protein molecules, owing to their contact with latex particles, are analyzed. Applicability of polyacrolein containing latexes for diagnostic purposes is discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1995.220060714
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