Gas permeability of copolypeptide membranes composed of γ‐methyl L‐glutamate and γ‐benzyl L‐glutamate

Abstract

AbstractMembranes of copoly(γ‐methyl L‐glutamate, γ‐benzyl L‐glutamate) (PMBLG) as well as the related homopolymer membranes were prepared, and permeabilities of oxygen, nitrogen, argon, and carbon dioxide were measured in the 0–70°C temperature range. The values of permeability coefficients and solubility coefficients of the copolymers were smaller than those of permeability coefficients and solubility coefficients of the two homopolymers for every gas studied. The diffusion coefficients of the gases showed a minimum at around 25 mole % benzyl glutamate. The temperature at a maximum of tan δ spectra for the membranes showed a maximum at around 25 mole % benzyl glutamate. The Arrhenius plots of diffusion coefficients and solubility coefficients for PMBLG, which contained 50 and 71 mole % benzyl glutamate, showed a break at about 50 and 40°C, respectively. This permeation behavior is explained by assuming a unique interaction between methyl glutamate and benzyl glutamate side chains.