Preparation and properties of A–B–A tri-block copolymer membranes consisting of N-hydroxypropyl-l-glutamine as the A component and l-alanine as the B component

A–B–A type tri-block copolymer consisting of N-hydroxypropyl-l-glutamine as the A component and l-alanine as the B component as well as the corresponding random copolymers and homopolymers were prepared by carrying out an aminoalcoholysis reaction with 3-amino-1-propanol, together with a crosslinking reaction with 1,8-octamethylenediamine on membranes of the starting polymer membranes including γ-methyl-l-glutamate residue. It was shown that the effective crosslink density was proportional to the percent crosslinker in the reaction mixture. The relation between their bulk structure and membrane properties were investigated, such as the swelling ratio in water (q), tensile properties, and enzymatic degradation behavior of the membranes in a pseudo-extracellular fluid (PECF). The tensile properties of the hydrophilic membranes were highly dependent on q in PECF, and on the hydrophobic portions in molecular chains, whose behavior was typical of an elastomer. Biodegradation of the membranes in vitro by bromelain indicated that the degradation took place in bulk rather than on the surface, and that the rate of degradation was also highly dependent on q in the samples as well as on the hydrophobic portion of the membranes in PECF.