Biodegradable polymers based on renewable resources. IV. Enzymatic degradation of polyesters composed of 1,4 : 3.6-dianhydro-D-glucitol and aliphaticdicarboxylic acid moieties

Enzymatic degradation of a series of polyesters prepared from 1,4:3.6-dianh ydro-D-glucitol (1) and aliphatic dicarboxylic acids of the methylene chain length ranging from 2 to 10 were examined using seven different enzymes. E nzymatic degradability of these polyesters as estimated by water-soluble to tal organic carbon (TOC) measurement is dependent on the methylene chain le ngth (m) of the dicarboxylic acid component for most of the enzymes examine d. The most remarkable substrate specificity was observed for Rhizopus dele mar lipase, which degraded polyester derived from 1 and suberic acid (m = 6 ) most readily. In contrast, degradation by Porcine liver esterase was near ly independent of the structure of the polyesters. Enzymatic degradability of the polyesters based on three isomeric 1,4:3.6-dianhydrohexitols and seb acic acid was found to decrease in the order of 1, 1,4:3.6-dianhydro-D-mann itol (2), and 1,4:3.6-dianhydro-L-iditol (3). Structural analysis of water- soluble degradation products formed during the enzymatic hydrolysis of poly ester 5g derived from 1 and sebacic acid has shown that the preferential es ter cleavage occurs at the O(5) position of 1,4:3.6-dianhydro-D-glucitol mo iety in the polymer chain by enzymes including Porcine pancreas lipase, Rhi zopus delemar lipase, and Pseudomonas sp. lipase. (C) 2000 John Wiley & Son s, Inc.