| Abstract: | Syntheses of copolymers composed of optically active depsipeptides (3,6‐dimethyl‐2,5‐morphorinedione) and L ‐lactide—poly(L ‐3,L ‐6‐dimethyl‐2,5‐morphorinedione‐co‐L ‐lactide), poly(L ‐3,DL ‐6‐dimethyl‐2,5‐morphorinedione‐co‐L ‐lactide), and poly(L ‐3,D ‐6‐dimethyl‐2,5‐morphorinedione‐co‐L ‐lactide)—were examined in an effort to improve the biodegradability and physical properties of homopoly(L ‐lactide). In degradation tests, the copolymers composed of 3,6‐dimethyl‐2,5‐morphorinedione and lactide in the ratios 10/90 to 13/87 exhibited high biodegradability toward proteinase K, whereas a homopolymer, poly(L ‐lactide), exhibited very poor biodegradability (only 50% after 200 h). These polymers composed of 3,6‐dimethyl‐2,5‐morphorinedione/L ‐lactide in 11/89 to 13/87 ratios also degrades rapidly after being in compost for 30 days. The resulting copolymers, however, showed relatively low elongation properties. Therefore, ternary copolymerizations of L ‐3,DL ‐6‐dimethyl‐2,5‐morphorinedione, ?‐caprolactone, and L ‐lactide were explored in an effort to improve their mechanical properties, especially the elongation, and sufficient results were obtained with an approximate ratio of 3/11/86. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 302–316, 2002 |
