ic9b03647_si_001.pdf (1.71 MB)
Enhancing Chain Initiation Efficiency in the Cationic Allyl-Nickel Catalyzed (Co)Polymerization of Ethylene and Methyl Acrylate
journal contribution
posted on 2020-03-19, 18:43 authored by Mengli Xu, Fan Yu, Pei Li, Guoyong Xu, Shaojie Zhang, Fuzhou WangImproving the efficiency of chain initiation is highly important
and also highly challenging in the development of olefin polymerization
catalysts. A series of 2-methylallyl-based nickel complexes supported
by aryl-N-bridged diphosphazane monoxide (PNPO) ligands
containing different electronic and steric substituents were prepared
and characterized. These nickel complexes are highly active single-component
catalysts for ethylene polymerization and copolymerization with methyl
acrylate (MA). 2-Methylallyl substituent on the μ-allyl catalysts led to an increase in the efficiency of chain initiation
compared with the corresponding allyl-based analogues, improving the
catalytic performances with high activity (up to 4.02 × 106 g PE (mol Ni)−1 h–1).
Linear polyethylenes with high molecular weight, narrow PDI values,
and high melting temperatures were generated. Most importantly, these
2-methylallyl nickel catalysts can promote ethylene-MA copolymerization
to afford functionalized polyethylenes with MA incorporation of up
to 7.0 mol %. The current work demonstrates that the change of initiating
units can lead to enhancement in catalyst performances. This provides
an alternative, simple, and potentially general strategy to improve
the properties of different catalyst systems.