Preparation and Properties of A-B-A Tri-Block Copolymer Membranes Consisting of N-Hydroxyalkyl L-glutamine as the A Component and L-Alanine as the B Component

Abstract

A-B-A type tri-block copolymer consisting of N-hydroxyalkyl 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 aminoalcoholysis reaction with 2-amino-1ethanol, 3-amino-1-propanol, or 5-amino-1-pentanol, together with crosslinking reaction with octamethylenediamine on membranes of the starting polymer membranes including y-benzyl-Lglutamate residue. The relation between their bulk structure and membrane properties was investigated, such as the swelling in water, aqueous vapor permeability, tensile properties, and enzymatic degradation behaviors of the membranes in PECF solution. The tensile properties of the hydrophilic membranes were highly dependent on the degree of swelling of PECF, and on the hydrophobicity of the side chains, whose behavior was typical of an elastomer. It was shown that a common relation was obtained between the rate of water vapor permeability and the degree of swelling of PECF of membranes in spite of the difference of the nature of the side chains. Biodegradation of samples in vitro by protease indicated that the degradation was a bulk rather than a surface phenomenon, and that the rate of degradation was also highly dependent on the degree of swelling of PECF of samples as well as on the hydrophobicity of the side chains of samples.KEY WORDS