Neutral Tridentate α-Sulfonato-β-diimine Nickel Catalyst for (Co)polymerizations of Ethylene and Acrylates

The development of highly tolerable metal catalysts to polar monomers is of fundamental importance for the metal-catalyzed copolymerization of ethylene and industrial polar vinyl monomers under mild conditions but still remains a scientific challenge. In this paper, a neutral tridentate α-sulfonato-β-diimine nickel catalyst with an apical SO3–Ni coordination was initially designed and synthesized in three dimensions. Combining advantages of cationic diimine and neutral phosphine-sulfonato-type catalysts, the α-sulfonato-β-diimine nickel catalyst showed good thermostability and controllability as well as high tolerance toward polar alkyl acrylates. Copolymerization of ethylene and methyl acrylate (MA) produced branched ethylene–methyl acrylate (EMA) copolymers with both high molecular weight (Mn > 20 × 103) and high MA incorporation (up to 10 mol %), whose branching structure was similar to commercial EMA industrially prepared by radical polymerization under harsh polymerization conditions. Density functional theory calculations were also performed to illuminate the formation of the EMA copolymer with terminal MA units.