Designing easily accessible tridentate hafnium catalysts for ethylene/1-octene copolymerization

Abstract

Polyolefin elastomers (POEs) have attracted widespread interest in both academia and industry as an important class of polyolefin material. Catalyst plays a critical role in the production of high-performance POEs. In this study, we design and synthesize a series of easily accessible tridentate pyridine amino hafnium catalysts with flexible ligands and study their properties in ethylene polymerization and copolymerization with 1-octene. These tridentate pyridine amino hafnium catalysts exhibited activity of up to 3.1 × 106 g mol−1 h−1, producing polyethylene with high molecular weight of up to 64.8 × 104 g mol−1 in ethylene polymerization at 150 °C. More importantly, these hafnium catalysts produced ethylene/1-octene copolymers with high comonomer incorporation of up to 12.9 mol% and molecular weight of up to 111.9 × 104 g mol−1(Mw), along with great mechanical properties (stress up to 17 MPa and strain up to 1000 %).