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

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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 16.3×106 g mol−1 h−1 and produced polyethylene with a high molecular weight of up to 24.5×104 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 72.7×104 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 187.6×104 g mol−1. The ease of synthesis, high versatility and great copolymerization properties of these hafnium catalysts make them highly attractive for future studies.

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