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:
Water vapor permeability of poly(γ-methyl L-glutamate) (PMLG) membranes prepared by using dichloroethane, trifluoroacetic acid, and formic acid as solvents was studied. The membranes prepared by casting dichloroethane and trifluoroacetic acid solutions of the polymer, designated as PMLG-DCE and PMLG-TFA, respectivley, had α-helical structures according to infrared absorption spectra, while the membranes prepared by allowing the PMLG-TFA membranes to swell in formic acid, designated as PMLG-FA, had mainly a β-sheet structure. The amounts of water sorbed by PMLG-DCE, PMLG-TFA, and PMLG-FA increased in that order. The isotherms of PMLG-TFA and PMLG-FA were sigmoidal-shaped isotherms, and the heat of sorption for PMLG-TFA and PMLG-FA was larger than that for PMLG-DCE, which suggested the presence of the sorption sites. The diffusion coefficients of water for PMLG-DCE increased and then decreased with increasing concentration. On the other hand, the diffusion coefficients for PMLG-TFA and PMLG-FA increased with concentration. The activation energies of diffusion for PMLG-DCE, PMLG-TFA, and PMLG-FA increased in that order. These results were discussed in connection with the molecular conformations of poly(γ-methyl L-glutamate) in the membranes. From these results, it is assumed that the molecular chains in the PMLG-TFA membranes are mainly in α-helical and partly random-coil conformations.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1979.070230918
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