Morphology and Melt Crystallization of PCL‐PEG Diblock Copolymers

ROP of PCL was realized in the presence of mPEG with M ₙ = 5 000, using Zn(La)2 as a catalyst. The resulting diblock copolymers with molar ratios of the CL/EO repeat units from 0.2–5.0 were characterized by DSC, WAXD, SEC, and 1H NMR. Melt crystallization was studied and analyzed with the Avrami equation. The spherulite growth rate G was determined at different crystallization temperatures. The G values were found to range between those of mPEG and PCL homopolymers. The morphology of an isothermally crystallized sample with CL/EO = 0.5 was examined. Spherulites with PCL embedded in PEG were observed, in contrast to concentric spherulites reported in the literature. magnified image