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

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 16.3x10(6) g mol(-1) h(-1) and produced polyethylene with a high molecular weight of up to 24.5x10(4) g mol(-1) in ethylene polymerization at 150 degrees C. More importantly, these catalysts produced ethylene/1-octene copolymers with incorporation of up to 13.7 mol % and molecular weight of up to 72.7x10(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 degrees C and molecular weight of up to 187.6x10(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.

Automated summary

Designed and synthesized bidentate pyridyl-amido hafnium catalysts exhibited high activity and high molecular weight in ethylene polymerization and copolymerization, showing great synthesis convenience and copolymerization properties.