Synthesis of novel pseudo amino acid/functional ε-caprolactone polyesters and photo-cross-linked networks

Novel copolymers of trans-4-hydroxy-4-proline (Hpr) and ε-caprolactones bearing protected functional groups (4-henzyloxy and 4-acryloyloxy) were synthesized via direct melt copolymerization with 1.5 wt% stannous octoate as catalyst at 140°C for 24 h. The synthesized copolymers were characterized by IR spectroscopy, proton nuclear magnetic resonance, diyfferential scanning calormietry and viscometry using Übbelohde type viscometer. The glass transition temperature (T_g) of the copolymers shifted to lower with increasing molar ratio of ε-caprolactone derivatives. The poly(N-benzyloxycarbonyl-Hpr-co-4-acryloyloxy-ε-caprolactone) beating a pendant acrylate groups can be cross-linked by ultraviolet light irradiation in the presence of benzyl diethyl ketal, giving a new biodegradable network.