Abstract
Ring-opening polymerization of e-caprolactone was realized in the presence of monomethoxy poly(ethylene glycol) (mPEG) with Mn = 5000, using Zn(La)2 as catalyst. The resulting PCL-PEG diblock copolymers with CL/EO repeat unit molar ratios from 0.2 to 5.0 were characterized by using DSC, WAXD, SEC, and 1H NMR. Melt crystallization was studied and the results analyzed with Avrami equation. The spherulite growth rate (G) was determined at different crystallization temperatures (Tc) ranging from 30 to 44 oC. The G values were found to range between those of mPEG and PCL homopolymers. The morphology of isothermally crystallized sample B with CL/EO=0.5 was examined. Interestingly, spherulites with PCL spherulites embedded in PEG ones were observed, in contrast to concentric spherulites reported in literature.