Parallel reactions in polymerization of ethylene/methyl methacrylate by late-transition-metal catalysts (α-diimine nickel)

Abedini, Ali; Jamjah, Roghayeh; Hassan, Abbas

doi:10.1007/s13726-021-00936-7

Cited by 1 publication

(1 citation statement)

References 39 publications

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“…As known, the [N, N] bidentate α-diimine Ni(II) and Pd(II) complexes bearing double-sided axial steric structures represent a mainstream catalytic system, which tend to yield high-molecular-weight polyethylene and ethylene-polar monomer copolymers. ( Dai et al, 2016a ; Gong et al, 2019a ; Guo et al, 2018 ; Meinhard et al, 2007 ; Rhinehart et al, 2013 ; Dai et al, 2015 ; Xia et al, 2020 ; Zhao et al, 2021 ; Wang et al, 2020a ; Zhang et al, 2013 ; Gong et al, 2019b ; Liao et al, 2019 ; Zhong et al, 2017a ; Zhong et al, 2017b ; Zhong et al, 2019 ; Abedini et al, 2021 ; Kanai et al, 2019 ; Zhang et al, 2020 ; Ma et al, 2021 ; Li et al, 2021a ; Allen et al, 2015 ). In contrast, pyridine-imine Ni(II) and Pd(II) catalysts often give rise to low-molecular-weight oligomers because the only unilateral axial steric hindrance rising from the imine motif hardly shields the metal well in most cases.…”

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confidence: 99%

Synthesis of High-Molecular-Weight Branched Polyethylene Using a Hybrid “Sandwich” Pyridine-Imine Ni(II) Catalyst

Cai

Wang

et al. 2022

Front. Chem.

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Most pyridine-imine Ni(II) and Pd(II) catalysts tend to yield low-molecular-weight polyethylene and ethylene-based copolymers in olefin insertion polymerization, as the unilateral axial steric structure of such complexes often cannot provide effective shielding of the metal center. In this study, we synthesized a series of hybrid “semi-sandwich” and “sandwich” type pyridine-imine Ni(II) complexes by incorporating diarylmethyl or dibenzosuberyl groups onto 8-aryl-naphthyl motif. The as-prepared Ni(II) complexes afforded highly branched polyethylene with high molecular weights (level of 105 g/mol), and moderate activities (level of 105 g/(molh)) in ethylene polymerization. Most interestingly, compared to “semi-sandwich” Ni(II) complexes bearing (2-diarylmethyl-8-aryl)naphthyl units, the “full-sandwich” counterpart containing (2-dibenzosuberyl-8-aryl)naphthyl motif was able to produce higher-molecular-weight polyethylene with higher branching density. In addition, the effect of remote non-conjugated electronic substituents in diarylmethyl groups of the Ni(II) system was also observed in ethylene polymerization.

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