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  • Chemistry  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Thermal and transport properties of copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate) (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1341-1351 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copoly(γ-stearyl L-glutamate-γ-methyl L-glutamate)s with various compositions were synthesized by ester exchange of poly(γ-methyl L-glutamate) with stearyl alcohol. The temperature dependence of the volume and helical spacing of the copolyglutamates thus prepared was examined from 0 to 100°C, observing the melting and crystallization of the long alkyl side chain attached to the polypeptide backbone. The melting temperature of the long side chain increased with increasing stearyl L-glutamate content. With increasing temperature, the α helical spacing decreased, especially with the melting of the side chain. On the other hand, the volume increased with increasing temperature and a marked increase was observed on melting. The above two phenomena were elucidated according to the structural model of the long side chain of the copolyglutamates proposed here. The transport properties, permeability coefficients were found to be considerably affected by the side-chain structure of the copolyglutamate and by the melting or crystallization of the side chain. The permeability coefficient of the copolyglutamate with 67% degree of stearylation, varied as much as two orders of magnitude before and after melting or crystallization. It was also confirmed that the permeability coefficient is controllable by the side-chain structural change of polypeptides.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080280603
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  • 2
    Electronic Resource
    Electronic Resource
    Circular dichroism of copoly(γ-stearyl-L-glutamate-γ-methyl-L-glutamate) (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1041-1048 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Copoly(γ-stearly-L-glutamate-γ-methyl-L-glutamate)s with various compositions were synthesized by the ester exchange reaction of poly(γ-methyl-L-glutamate). Circular dichroism studies were carried out for solution and solid film as a function of the degree of stearylation and temperature. The slight and gradual temperature dependence of molecular ellipticity was observed for solution of all the copolyglutamates studied here and for the solid film of the copolyglutamate with the degree of stearylation of 16%, indicative of no reversal in the helix sense. However the remarkable change in negative molecular ellipticity with temperature was detected for the solid film of the copolyglutamate with a low degree of stearylation, e.g., 52%, whereas the drastic change in molecular ellipticity from a negative to positive value appeared for that with a higher degree of stearylation. This is discussed in terms of the reversal in the helix sense from a right- to left-handed α helix with the increase of temperature occurring at the melting temperature of the ordered side chain region.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250410
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of side chain structure on sorption of xenon and carbon dioxide gas by polypeptide membranes (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 279-288 
    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: The influence of side chain structure on sorption of xenon and carbon dioxide gas by polypeptides is examined in two ways: chemical structure of side chain and higher order structure of the side chain region. Sorption of xenon gas increases progressively with increase in side chain length of poly(n-alkyl L-glutamates). The sorption isotherms of a polymer at various temperatures are reduced to one curve when the data are arranged in the form of sorption per residue versus fugacity ratio (as activity). The sorption of carbon dioxide gas shows a minimum at an intermediate length of side chains, corresponding to poly(n-propyl or n-butyl glutamate). The behavior is considered the result of overlapping influences of looseness of the side chain region and density of polar groups. The Langmuir constants and the enthalpy and entropy of sorption explain this quantitatively. Sorption of carbon dioxide gas is influenced by the higher-order structure of poly(γ-benzyl L-glutamate). In this polymer, the benzyl ester part is the main sorption site, and it was confirmed that the stacking between side-chain benzene rings significantly reduces the extent of sorption.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1978.070220120
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  • 4
    Electronic Resource
    Electronic Resource
    O2 and N2 gas permselectivity of alternating copoly(vinylidene cyanide-vinyl acetate) (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1333-1340 
    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: The sorption and permeation of oxygen and nitrogen in and through alternating copoly(vinylidene cyanide-vinyl acetate) [copoly(VDCN-VAc)] (Tg = 176°C) membranes annealed for different periods just below Tg, 160°C, were investigated over the pressure range from 100 to 1000 cmHg. The dual-mode sorption and mobility models were used to analyze the results. A sub-Tg annealing of copoly(VDCN-VAc) caused a slight decrease in the amount of sorption in the membranes. This decrease in the amount of oxygen and nitrogen sorption can be attributed to a decrease in the Langmuir sorption capacity term, C′H, with increasing sub-Tg annealing period. The densification of copoly(VDCN-VAc) membranes caused simultaneously by the annealing remarkably reduced diffusion coefficients for both gases. The reduction in diffusion coefficients of Langmuir mode, DH, for both gases was found to be larger than that of Henry's law mode, DD. Furthermore, permselectivity of oxygen to nitrogen, the ratio of permeability coefficient of oxygen to nitrogen (PO2/PN2), reached to 11.8 for the copoly(VDCN-VAc) annealed for 30 h. Evidently the reduction of DH and DD for nitrogen with increasing annealing period was much larger than that for oxygen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350518
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  • 5
    Electronic Resource
    Electronic Resource
    Compatibility of polypeptide blends of poly(γ-butyl glutamate)/poly(γ-benzyl glutamate) (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 4279-4285 
    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: The compatibility of poly(γ-butyl glutamate)/poly(γ-benzyl glutamate) blend was examined by the estimation of the side chain dispersion of polypeptides in terms of the condition of preparation of blend films and the blend ratio. The polypeptide blend prepared for very short casting time exhibited an apparent compatibility. On the other hand, the polypeptide blend cast for long time did show incompatibility, irrespective of the blend ratio or mole fraction. The structures of the separated phase changed around mole fraction of 0.5 with the increasing mole fraction. The poly(γ-butyl glutamate) island phase transformed into the poly(γ-benzyl glutamate) island phase with increasing mole fraction of poly(γ-benzyl glutamate) according to the calculation of the simple island-matrix model by Takayanagi et al.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291256
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  • 6
    Electronic Resource
    Electronic Resource
    The crystallization and formation of cluster of ethylene ionomer during physical aging (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 2393-2402 
    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: The effect of the physical aging of ethylene ionomers was studied for the samples with the acid content of 5.4 mol%, and the degree of neutralization, 0%, 60% Na, 60% Zn, and 90% Zn. The information about the crystal and the cluster part of the physically aged ionomers was obtained by differential scanning calorimetry and by dynamic viscoelastic measurements, respectively. The degree of crystallinity and the dynamic modulus for the ionomers of the degree of neutralization 0%, 60% Na and 60% Zn increased gradually with the aging time; on the other hand, the crystallinity of 90% Zn remained constant and the modulus at 100°C increased to a certain value up to a period of 100 h, but thereafter the crystallinity increased remarkably and the modulus remained. These facts indicate that the crystallization of neutralized ethylene ionomer starts after clustering and the clustering would finish at early stage of the physical aging for intermediately neutralized ethylene ionomer. The physical aging effect of the ethylene ionomers was, thus, found to be important to material design.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330710
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  • 7
    Electronic Resource
    Electronic Resource
    Permeability of water vapor and carbon dioxide gas through poly(n-alkyl L-glutamate) (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 1443-1450 
    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: To elucidate the permeation mechanism in polypeptide membranes, permeation of water vapor and carbon dioxide gas through a series of poly(n-alkyl L-glutamate) (polymers of methyl, ethyl, propyl, butyl, amyl, hexyl, and octyl glutamate) were studied. It was confirmed that diffusion of small molecular substances in polypeptides takes place through the side chain region between helices. The diffusion coefficient of carbon dioxide gas increases with increase in side chain length. As for water vapor, the diffusion coefficient is highest with poly(n-butyl glutamate), and the clustering effect of water may contribute to the diffusion coefficient with increase in the hydrophobic nature of the polymer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1974.070180515
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  • 8
    Electronic Resource
    Electronic Resource
    Sorption and permeation behavior of water vapor and carbon dioxide gas through ethylene ionomer membranes (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 3335-3343 
    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: Sorption and permeation of water vapor and carbon dioxide gas through ethylene ionomer membranes were studied as a function of pressure. Water sorption increased with an increase of the acid content and especially degree of neutralization of ethylene ionomers. The sodium salt ionomer enhanced water sorption compared to the zinc salt ionomer. However, there was no remarkable difference of permeability coefficient of water vapor through the sodium and zinc ionomer membranes. Diffusion coefficient of the sodium salt ionomer is one order smaller than that of zinc salt ionomer, corresponding to an immobilized water structure in the sodium salt ionomer. Differential scanning calorimetry studies on water sorbed to membrane manifested that water sorbed was almost nonfreezable. Sorption of carbon dioxide gas in ethylene ionomers was a dual-mode type. The pressure dependence of permeability coefficient of carbon dioxide gas was interpreted in terms of a partial immobilization model, independent of the kind of the metal salt in ethylene ionomer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320135
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  • 9
    Electronic Resource
    Electronic Resource
    Gas permeability of the racemic form of poly(γ-benzyl glutamate) (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1197-1206 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption of carbon dioxide gas by a film of the racemic form of poly(γ-benzyl glutamate) was observed over the temperature range from 10 to 40°C and the permeability coefficient of carbon dioxide gas through the film was measured over the temperature range from 30 to 120°C. Different sorption isotherms were obtained in the ranges above and below the glass-like transition temperature, respectively. The result indicates that the sorption behavior is influenced by the side chain mobility. The amount of sorption by the racemic form of poly(γ-benzyl glutamate) does not vary with the intermolecular benzene ring stacking, but is similar to that of the form C of poly(γ-benzyl-L-glutamate) which contains no stacking. The breakdown of the intermolecular benzene ring stacking, which was confirmed by X-ray diffraction analysis and differential scanning calorimetry, results in an abrupt increase of the permeability and the diffusion coefficients, and conversely the formation of the stacking leads to an abrupt decrease in the permeability and the diffusion coefficients. Below the transition temperature, the permeability coefficient of the racemic form of poly(γ-benzyl glutamate) is smaller than that of the forms A, B, and C of poly(γ-benzyl-L-glutamate), related to the benzene ring stacking. The diffusion coefficient was estimated from the free volume theory, and the calculated value was compared with the value obtained from the permeability and the solubility coefficients. The fractional free volume was estimated to be about 0,068, when the best fit between the experimental and the calculated diffusion coefficients was obtained by a trial and error method.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820419
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  • 10
    Electronic Resource
    Electronic Resource
    Miscibility and volume changes of mixing in the polystyrene/poly(2-chlorostyrene) blend system (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 415-422 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The specific volume-temperature relationships of polystyrene, poly(2-chlorostyrene), and their polymer blends as well as the volume change of mixing Δvm of the blends were obtained in the liquid state by dilatometry. The equation of state parameter and the molecular parameter of each homopolymer and blends were determined according to the lattice fluid theory of Sanchez and Lacombe. The experimental Δvm obtained agreed quite well with that predicted from theory, and the enthalpy of mixing ΔHm was also predicted using the pair molecular parameter. These two values were negative, indicative of miscibility of polystyrene and poly(2-chlorostyrene) in the liquid state. The absolute values of Δvm and ΔHm were about twice those for polystyrene and poly(phenylene oxide) blend, suggesting a specific interaction between the two polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250212
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