Preparation of Comb-Shaped Polyolefin Elastomers Having Ethylene/1-Octene Copolymer Backbone and Long Chain Polyethylene Branches via a Tandem Metallocene Catalyst System

A novel type of comb-branched ethylene/1-octene copolymer elastomers (CPOEs) was synthesized, and their properties were systematically investigated in this work. The polymers had crystalline polyethylene (PE) long chain branches attached to amorphous ethylene/ 1-octene random copolymer backbones. The unique structure was generated through a tandem catalyst system consisting of a Zr ligated with phenoxycycloalkylimine (FI-Zr) and a constrained geometry catalyst (CGC-Ti). Linear PE macromonomers, with over 88% chains terminally unsaturated, were synthesized with the FI-Zr catalyst, while the CGC-Ti catalyst was employed in the copolymerization of ethylene, 1-octene, and the PE macromonomer. The resulting CPOEs possessed high melting temperature (>120 degrees C) and low glass transition temperature (<-60 degrees C), suggesting a phase separation occurred in the copolymer system. The measurement of mechanical properties showed that the elongation at break reached >1200%. Some samples performed better strain recovery than the commercial POE Engage 8150.