Hydrolytic degradation of poly(oxyethylene)/poly(e-caprolactone) multiblock copolymers
Résumé
The degradation of poly(oxyethylene)/poly(e-caprolactone) (POE/PCL) multiblock copolymers was investigated at 37°C in a 0.13M pH=7.4 phosphate buffer selected to mimic in vivo conditions. The copolymers were obtained by coupling polycaprolactone diols and poly(ethylene glycol) diacids, using dicyclohexylcarbodiimide as coupling agent. Various techniques such as weighing, SEC, IR, 1H NMR, DSC and X-ray diffractometry were used to monitor changes in total mass, water absorption, molar mass, thermal properties, degree of crystallinity and composition. The results showed that introduction of POE sequences considerably increased the hydrophilicity of the copolymers as compared with PCL homopolymers. Nevertheless, the degradability of PCL sequences was not enhanced due to the phase separation between the two components. Significant morphological changes were also observed during the degradation.