Issue 1, 2023

A rigid–flexible double-layer steric strategy promoting ethylene polymerization and copolymerization in alkane solvents

Abstract

In this study, a series of double-layered steric α-diimine nickel and palladium complexes containing bulky diarylmethyl moieties with remote 4-cycloalkyl and -phenyl substituents were designed and synthesized. The as-synthesized nickel complexes showed high activities (ca. 106 g mol−1 h−1) and superior thermal stability, giving access to moderately branched polyethylenes with high molecular weights and narrow molecular weight distributions at high temperatures. With the rigid–flexible double-layered steric nickel catalysts, high temperature living polymerizations at 80 °C were achieved. The polyethylene materials yielded by these nickel catalysts at 80 °C exhibited outstanding tensile mechanical and elastic recovery properties (SR up to 86%). Correspondingly, the palladium complexes displayed moderate activities in ethylene polymerization, producing moderately branched polyethylenes with high molecular weights. The polyethylene materials yielded by palladium complexes at 60 °C exhibited good tensile mechanical properties and moderate elastic recovery values. In addition, these palladium complexes could also promote ethylene-polar monomer copolymerization, albeit with modest activity, yielding polar functionalized polyethylenes with moderate levels of branching densities, molecular weights, and incorporation ratios. Overall, the rigid–flexible double-layered steric nickel and palladium complexes with remote cyclohexyl substituents were found to have significantly higher activities than their rigid–rigid double-layered steric or monolayered dibenzhydryl counterparts in alkane solvents.

Graphical abstract: A rigid–flexible double-layer steric strategy promoting ethylene polymerization and copolymerization in alkane solvents

Supplementary files

Article information

Article type
Research Article
Submitted
02 Sep 2022
Accepted
01 Nov 2022
First published
01 Nov 2022

Inorg. Chem. Front., 2023,10, 108-117

A rigid–flexible double-layer steric strategy promoting ethylene polymerization and copolymerization in alkane solvents

W. Lu, W. Fan and S. Dai, Inorg. Chem. Front., 2023, 10, 108 DOI: 10.1039/D2QI01895K

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