Synthesis and characterization of three-arm poly(fi-caprolactone)-based poly(ester urethanes) with shape-memory effect at body temperature

Abstract

Novel biodegradable star poly(ester urethanes) containing three-arm poly(fi-caprolactone) (PCL) as switching segment were prepared as shape-memory polymers (SMPs) with switching temperature (Ts) around body temperature. PCL-triols with molecular weight (Mn) of 2700 4200 g/mol and Tm of 45 47 °C were synthesized in 55 67% yield by Novozym 435-catalyzed ring-opening polymerization of fi-caprolactone with glycerol as initiator, and their three-arm structures were confirmed by 1 H and 13 C NMR analysis. Reaction of the PCL-triols with methylene diphenyl 4,4fi-diisocyanate isocynate and 1,6-hexanediol gave three-arm PCL-based poly(ester urethane)s (tPCL-PUs) in 83 92% yield, with 65 75% soft segment. The structure of tPCL-Pus was confirmed by 1 H NMR analysis, and the thermal properties were analyzed by DSC with Ts of 36 39 °C. tPCL-PUs showed excellent shape-memory effects at 38 °C during cyclic thermomechanical tensile tests: shape recovery within 10 s, shape fixity rate of 92%, and shape recovery rate of 99%. The novel biodegradable star SMPs are potentially useful in biomedical applications. © 2009 American Chemical Society.