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%.

过渡金属催化剂的合成与设计在乙烯聚合领域受到了广泛关注。本工作设计并合成了一系列带有醚类取代基的α-二亚胺镍催化剂（Ni1–Ni4）。通过改变醚基结构，系统地调控了这些催化剂的空间位阻，而该因素直接影响其乙烯（共）聚合性能。这些催化剂展现出极高的催化活性，最高可达107 g·mol⁻¹·h⁻¹。所得聚乙烯的支化密度范围宽泛（22至92/1000C），聚合物分子量较高，最高可达59.8×10⁴ g·mol⁻¹。由Ni1和Ni2制备得到的聚乙烯展现出优异的力学性能与弹性回复性能。此外，该系列催化剂可高效催化乙烯与多种极性单体的共聚反应，所得共聚物的单体掺入率范围为0.24%至1.43%。