Chain microstructure, crystallization, and morphology of olefinic blocky copolymers

摘要

The chain microstructure, crystallization, and morphology of three olefinic blocky copolymers (OBCs) are compared. The weight percentage of the hard block and the octene content in it are calculated from the ~(13)C NMR spectra with a two-site first-order Markovian model. The lengths of the hard blocks are compared from the melting and crystallization behaviors. The remarkable difference between the crystallinity measured by DSC, and wide-angle X-ray diffraction (WAXD) indicates the presence of partially ordered phases. Small angle X-ray scattering (SAXS) shows that the partially ordered phases in OBC-A are mainly located at the interface between the crystalline and amorphous phases, but exist as separated microdomains in OBC-B. As the hard block becomes shorter, there are also more, separated partially ordered phases in OBC-C. Spherulites are observed in all OBCs by POM and the size of the spherulites decreases in the order: OBC-A > OBC-B > OBC-C. TEM shows that spherulites are poorly developed in a thin film of OBC-B.