FURTHER-STUDIES ON BIODEGRADATION OF ALIPHATIC POLY(ESTER-AMIDES)

Two types of aliphatic poly(ester-amides) (PEAs) were subjected to microbial degradation in basal mineral salt broth, under the attack of a yeast, Cryptococcus laurentii, at 20 degrees C. PEA-I copolymers were made by the anionic ring-opening copolymerization of of epsilon-caprolactone and epsilon-caprolactam, whereas PEA-II copolymers were synthesized by a two-step polycondensation reaction of hexanediol-1,6, hexanediamine-1,6, and adipoyl chloride. These copolymers were found to be readily degradable under biotic conditions, based on weight loss, GPC, NMR spectroscopy, and tensile property measurements. Compared to abiotic hydrolysis, biodegradation occurred much faster under milder conditions. Furthermore, NMR spectroscopic analysis proved that the biodegradation of poly(ester-amides) involves the enzymatic hydrolysis of ester groups on the backbones of polymers into acid and hydroxyl groups. No breakdown of amide bonds was observed under the given biotic conditions. (C) 1993 John Wiley & Sons, Inc.