Biodegradable shape-memory polymer-polylactideco-poly(glycolide-co-caprolactone) multiblock copolymer

In this study, biodegradable shape-memory polymers-polylactide-co-poly(glycolide-co-caprolactone) multiblock (PLAGC) copolymers-were synthesized by the coupling reaction of both macrodiols of polylactide (PLLA-diol) and poly(glycolide-co-caprolactone) (PGC-diol) in the presence of 1,6-hexanediisocyanate as coupling agent. The copolymers formed were found to be thermoplastic and easily soluble in common solvents. The compositions of the copolymers were determined by H-1-NMR and the influences of segment lengths and contents of both macrodiols on the properties of the PLAGC copolymers were investigated. It was found that the copolymers had adjustable mechanical properties which depended on contents and segment lengths of both macrodiols. The copolymers showed such good shape-memory properties that the strain fixity rate (R-f) and the strain recovery rate (R-r) exceed 90%. By means of adjusting the compositions of the copolymers, PLAGC copolymers with transition temperatures around 45 degrees C could be obtained. The degradation rate determination showed that the PLAGC copolymers have fast degradation rates, the mechanical strengths of the PLAGC copolymers would be completely lost within 1-2 months depending on molecular weights and contents of the both segments of PLLA and PGC. Copyright (c) 2005 John Wiley & Sons, Ltd.