Enzymatic degradation of block copolymerase prepared from ε-caprolactone and poly(ethylene glycol)

Abstract

Block copolymers were prepared by ring-opening polymerization of ε-caprolactone in the presence of monohydroxyl or dihydroxyl poly(ethylene glycol) (PEG), using Zn powder as catalyst. The resulting poly-(ε-caprolactone) (PCL)-PEG diblock and PCL-PEG-PCL triblock copolymers were characterized by various analytical techniques such as NMR, size-exclusion chromatography, differential scanning calorimetry, and X-ray diffraction. Both copolymers were semicrystalline polymers, the crystalline structure being of the PCL type. Films were prepared by casting dichloromethane solutions of the polymers on a glass plate. Square samples with dimensions of 10 × 10 mm were allowed to degrade in a pH = 7.0 phosphate buffer solution containing Pseudomonas lipase. Data showed that the introduction of PEG blocks did not decrease the degradation rate of poly(ε-caprolactone).