Hydrogen-Bonding-Induced Heterogenization of Nickel and Palladium Catalysts for Copolymerization of Ethylene with Polar Monomers.

Abstract

The practical synthesis of polar-functionalized polyolefins using transition-metal-catalyzed copolymerization of olefins with polar monomers is a challenge; the use of heterogeneous catalysts is little explored. Herein, we report the synthesis of heterogeneous naphthoquinone-based nickel (Ni/SiO2 ) and palladium (Pd/SiO2 ) catalysts through hydrogen bonding interactions of the ligands with the silica surface. Ni/SiO2 exhibits high activities (up to 2.65×106 g mol-1 h-1 ) during the copolymerization of ethylene with 5-hexene-1-yl-acetate, affording high-molecular-weight (Mn up to 630 000) polar-functionalized semicrystalline polyethylene (comonomer incorporation up to 2.8 mol %), along with great morphology control. The resulting copolymers possess improved surface properties and great mechanical properties. Pd/SiO2 can mediate ethylene copolymerization with polar monomers with moderate activity to produce high-molecular-weight copolymers with tunable comonomer incorporation.