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:
Gas permeability of poly(γ-methyl L-glutamate) (PMLG) membranes prepared by using dichlorethane, 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, respectively, 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 diffusion coefficients of each gas studied for PMLG - DCE, PMLG - TFA, and PMLG - FA decreased in that order, and the apparent activation energies of diffusion increased in that order. The apparent heats of solution for Ne,O2, N2, and CO2 were negative in PMLG - FA. These results were discussed in connection with the molecular conformations of PMLG in the membranes. It is suggested that the diffusion of gases in PMLG - DCE takes place in the side-chain regions between helices, while in PMLG - FA the diffusion occurs across the polymer main chain whose mobility is depressed by the intermolecular hydrogen bonds. The effect of water on oxygen permeability of PMLG - DCE was small; on the contrary that of PMLG - FA was very large. Furthermore, it is assumed that the random-coil conformation partly exists in PMLG - TFA.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1982.070270320
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