Wenbing Wang

This study designed and synthesized a series of aniline with different steric hindrances at the ortho‐position and electron variable substituents on the diphenylmethyl group and synthesized corresponding pyridine ‐ imine ligands and nickel catalysts (Ni1‐Ni9). These nickel catalysts exhibited high activity in ethylene polymerization (up to 17.0 × 10 ⁶ g·mol ⁻¹ ·h ⁻¹ ), producing polyethylene wax with molecular weights ranging from 5.3 × 10 ³ to 12.4 × 10 ³ g·mol ⁻¹ . It was found that both the ortho‐steric hindrance and remote electron effects in the ligand significantly influenced the polymerization performance. Specifically, reduced steric hindrance and the presence of electron‐withdrawing substituents at the remote position enhanced the ethylene insertion rate, whereas increased steric hindrance improved the thermal stability of the catalysts. Furthermore, these catalysts were effective in the copolymerization of ethylene with 10‐undecylenic acid, yielding polar polyethylene wax with a comonomer incorporation of 0.40 to 1.13 mol% and molecular weights of 5.7 × 10 ³ to 7.2 × 10 ³ g·mol ⁻¹ .

Recently, a series of inexpensive nickel‐based phosphine phenol catalysts have been synthesized for catalyzing the copolymerization of ethylene and polar monomers to prepare functionalized polyolefins. However, it is still challenging to achieve homogeneous nickel catalysts that catalyze ethylene polymerization or copolymerization at high temperatures (up to 150°C) with high activity. This work synthesized a series of phosphine phenol nickel catalysts with bulky steric hindrance and electron donating groups, which were used for catalyzing ethylene polymerization and coordination copolymerization of ethylene and a series of polar monomers at high temperatures. These nickel catalysts exhibited high ethylene polymerization activity and excellent thermal stability at 150°C, producing polyethylene with a molecular weight of up to 102.7 × 10⁴ g mol⁻¹. More importantly, these catalysts can catalyze the copolymerization of ethylene and a range of polar monomers at 120°C, improving the surface properties of polyolefins.

In recent years, phosphorus phenol nickel catalysts with excellent polar monomer copolymerization performance have flourished. A series of phosphorus phenol nickel catalysts based on adjusting spatial hindrance have been designed and synthesized for ethylene polymerization and copolymerization. In this paper, a series of phosphorus phenol nickel catalysts with different para electronic effects have been designed from the perspective of electronic effects, and the effects of these phosphorus phenol nickel catalysts with different electronic effects on ethylene polymerization and copolymerization have been studied. And we found that these nickel catalysts with para electron donating groups have higher catalytic activity (the highest activity can reach 6.2 × 10⁶ g_PE mol_Ni⁻¹ h⁻¹) and prepared polymers with higher molecular weight (molecular weight up to 4.9 × 10⁵ g_PE mol_Ni⁻¹) compared to electron withdrawing groups.