Characterization and Modeling of Metallocene-Based Branch−Block Copolymers

Abstract

The nature of polyolefin branch−block copolymers produced using mixed-metallocene catalysts has been further characterized in an attempt to relate polymer microstructure to properties. These copolymers were synthesized by incorporating vinyl-terminated, crystallizable macromonomers into amorphous backbones. It was shown that polymer properties depended strongly on the fine details of the polymerization procedure (sequential or ex-situ vs simultaneous or in-situ). Here we present rheological, chromatographic, and thermal data along with polymerization kinetic model simulations to interpret the observed property differences between ex-situ and in-situ produced polymers.