SYNTHESIS AND PROPERTIES OF HYDROPHILIC COPOLYPEPTIDE MEMBRANES CONTAINING L-ASPARTIC ACID AS ONE-COMPONENT

Three‐component random copolypeptide consisting of N‐hydroxypropyl‐L‐glutamine, L‐aspartic acid, and L‐lysine, related two component random copolypeptides and homopolypeptides, were prepared by carrying out aminolysis reaction with 3‐amino‐1‐propanol, followed by crosslinking reaction with 1,8‐octamethylenediamine on starting polymer membranes consisting of γ‐methyl‐L‐glutamate, L‐aspartic acid, and L‐lysine. The effective crosslink density was shown to be proportional to the content of the crosslinker in the reaction mixture. The tensile properties of these hydrophilic membranes were highly dependent on the degree of swelling in the pseudoextracellular fluid, hydrophobicity of the side chains, and the effective charge density of membranes, and their behavior was typical of an elastomer. A higher rate of water permeability was obtained with charged membranes than noncharged and/or compensated charged membranes with the same order of the degree of swelling in the pseudo‐extracellular fluid. Biodegradation of the samples in vitro by papain indicated that the degradation could be regarded as a bulk rather than a surface phenomenon. The rate of degradation was also highly dependent on the degree of swelling of membranes, as well as on the hydrophobicity and the effective charge density of side chains of sample membranes. Copyright © 1990 John Wiley & Sons, Inc.