Hydrolytic degradation of poly(oxyethylene)-poly-(epsilon-caprolactone) multiblock copolymers

摘要

The degradation of poly(oxyethylene)-poly(epsilon-caprolactone) (POE-PCL) multiblock copolymers was investigated at 37 degrees C in a 0.13 M, 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, size exclusion chromatography, infrared, H-1 nuclear magnetic resonance, differential scanning calorimetry, 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. (C) 1998 John Wiley & Sons, Inc. [References: 21]