Ethylene (Co)Polymerization Catalyzed by α‑Diimine Nickel Catalysts Bearing Ether Substituents

The synthesis and design of transition metal catalysts have attracted extensive attention in ethylene polymerization. In this work, a series of α-diimine nickel catalysts (Ni1-Ni4) bearing ether substituents were designed and synthesized. The steric hindrance of these catalysts was systematically modulated by varying the ether groups, which directly influenced their ethylene (co)-polymerization performances. These catalysts showed exceptionally high activities (up to 10⁷ g·mol^-1·h^-1). The resulting polyethylene displayed a broad range of branching densities (22 to 92/1000C) and high polymer molecular weights (up to 59.8×10⁴ g·mol^-1). Polyethylene produced by Ni1 and Ni2 exhibited outstanding mechanical properties and elastic recovery performance. Furthermore, these catalysts efficiently catalyzed ethylene copolymerization with diverse polar monomers, yielding copolymers with incorporation ratios ranging from 0.24% to 1.43%.