Enhancing Chain Initiation Efficiency in the Cationic Allyl-Nickel Catalyzed (Co)Polymerization of Ethylene and Methyl Acrylate

Abstract

Improving 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 × 10 6 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.

Living Chain-Walking (Co)Polymerization of Propylene and 1-Decene by Nickel α-Diimine Catalysts

“…In the field of polyolefin research [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], many studies have reported on the homopolymerization of ethylene [ 21 , 22 , 23 , 24 ], different higher 1-alkene [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ], and linear internal alkenes [ 32 , 33 , 34 ] using Brookhart-type α-diimine nickel and palladium catalysts [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ] because of the chain-walking process [ 42 , 43 , 44 , 45 ]. The interest in highly branched polyolefins such as dendrimer and hyper branched polymers has increased obviously in recent years owing to these unique physical properties, chemical properties, and their potential applications as adhesives, lubricants, and paints [ 7 ].…”

Microstructural, Thermal and Electrical Properties of Methyl Methacrylate and 1‐Hexene Copolymers Made by Dinuclear Ni‐Based Catalysts

“…Mononuclear nickel and palladium catalysts were used in this type of polymerization and showed diverse catalytic activity against polar monomers [5,11–16] . Mostly, these structures were based on α‐diimine ligands used for copolymerization of α‐olefin with polar monomers [17–23] .…”

Ortho-Functionalized Dibenzhydryl Substituents in α-Diimine Pd Catalyzed Ethylene Polymerization and Copolymerization

“…Polyolefins have been the world's largest produced synthetic polymers [1]. Late-transition-metal catalysts can mediate olefin copolymerization with polar monomers [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], providing a direct and potentially economic way to access functionalized polyolefins with some improved properties as well as some unique functions [22][23][24][25][26][27][28][29][30][31]. In the 1990s, Brookhart et al reported the studies of α-diimine Pd catalysts for olefin polymerization and copolymerization with polar monomers (Chart 1A) [32][33][34].…”