Bidentate Pyridyl‐Amido Hafnium Catalysts for Copolymerization of Ethylene with 1‐Octene and Norbornene

Abstract Polyolefin elastomers ( POEs ) and cyclic olefin copolymers ( COCs ) are high‐performance polyolefin materials of wide interest. It is crucial to develop low‐cost and high‐performance transition metal catalysts to prepare these polyolefin materials. In this contribution, we designed and synthesized a series of bidentate pyridyl‐amido hafnium catalysts and used them in ethylene polymerization and copolymerization with comonomers including 1‐octene and norbornene. These catalysts exhibited high activities of up to 16.3×10 6 g mol −1 h −1 and produced polyethylene with a high molecular weight of up to 24.5×10 4 g mol −1 in ethylene polymerization at 150 °C. More importantly, these catalysts produced ethylene/1‐octene copolymers with incorporation of up to 13.7 mol % and molecular weight of up to 72.7×10 4 g mol −1 , and prepared ethylene/norbornene copolymers with incorporation of up to 50.3 mol %, along with glass transition temperature of up to 184.3 °C and molecular weight of up to 187.6×10 4 g mol −1 . The ease of synthesis, high versatility and great copolymerization properties of these hafnium catalysts make them highly attractive for future studies.