Promoting Ethylene (co)Polymerization in Aliphatic Hydrocarbon Solvents Using tert‐Butyl Substituted Nickel Catalysts

Abstract

Comprehensive SummaryIn the past few decades, the development of high‐performance catalysts has been a key driving force and a center of research efforts in the field of olefin polymerization. However, a major discrepancy exists between industrial researches which utilize aliphatic hydrocarbon solvents, and academic researches which predominantly focus the catalytic properties in aromatic solvents. In this contribution, a novel diaryl‐methyl aniline bearing eight tert‐butyl groups was prepared and subsequently transformed to four different kinds of imine‐type ligands. The corresponding nickel complexes as well as their counterparts derived from diphenyl‐methyl aniline without the tert‐butyl groups were prepared and investigated in ethylene polymerization. The multiple tert‐butyl groups enable great solubility of the metal complexes in aliphatic hydrocarbon solvents, leading to similar polymerization properties comparing with aromatic solvents. In contrast, their counterparts without tert‐butyl groups demonstrate significant solvent effect. Moreover, the ligand electronic and steric effects induced by the tert‐butyl groups lead to nickel catalysts with great thermal stability (up to 140 oC) and capabilities of generating high molecular weight polymer and copolymer products. This tert‐butyl strategy can be potentially applied to many different polymerization catalyst systems and help to bridge academic studies with practical applications.