Degradable polyurethanes containing poly(butylene succinate) and poly(ethylene glycol)

Biodegradable polyurethanes may be used in the fabrication of plastic films which can replace common films prepared from nondegradable polymers such as polyethylene and polypropylene. Prepolymers were synthesized from poly(butylene succinate) polyol (PBS, M-n 1650), poly(ethylene glycol) (PEG, M-n 1000), and 4,4'-dicyclohexylmethane diisocyanate, and reacted with 1,4-butanediol chain extender to obtain polyurethanes. Their number-average molecular weights and melting temperatures are in the range of 30,000-38,000 and 99-101 degreesC, respectively. The tensile strengths (2.0-2.4 kg/mm(2)) of the polymers were somewhat greater than the reported value (1.6 kg/mm(2)) of PBS with a comparable molecular weight (M-n 20,000). However, their elongations at break (230-330%) were significantly greater than that of the PBS (42%). They were hydrolytically degradaded very rapidly in 3% NaOH solutions at 37 degreesC such that their weight loss was approximately 30-60% within 2 days, depending on the content of PEG and hard segment. On the other hand, polyurethanes containing only PBS as soft segments showed a much slower degradation rate under the identical conditions. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.