Photoresponsive α-Diimine Nickel Modulated Ethylene (Co)Polymerization  

作　　者：Jingshuang Yang Xiaoqiang Hu Zhongbao Jian 

机构地区：[1]State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Renmin Street 5625,Changchun,Jilin,130022 China [2]University of Science and Technology of China,Hefei,Anhui,230026 China

出　　处：《Chinese Journal of Chemistry》2022年第24期2919-2926,共8页中国化学（英文版）

基　　金：support from the National Natu-ral Science Foundation of China(Nos.22122110 and 21871250).

摘　　要：Beyond the single ligand electronic and/or steric modifications, external stimuli are a useful tool for modulating catalytic polymerization reactions. Light stands out from external stimuli, but the corresponding photoresponsive transition metal catalysts are significantly rare for olefin polymerization due to the difficult synthesis. In this contribution, in consideration of the key role of steric shielding on the axial sites, we installed four concerted azobenzene moieties into symmetrically terphenyl-based α-diimine Ni(II) complexes to prepare photoresponsive catalysts, which were applied to ethylene polymerization and copolymerization with polar monomer. Via the trans-cis isomerization of azobenzene-functionalized Ni(II) catalysts in dark or under UV light, catalytic activity, polymer molecular weight, branching density, incorporation of co-monomer, and even the ratio of branching pattern were significantly modulated in ethylene (co)polymerizations. This photo-controlled strategy behaved an opposite influence between ethylene polymerization and copolymerization, in terms of catalytic activity and polymer molecular weight. As a result, slightly branched ultrahigh molecular weight polyethylenes and high molecular weight functionalized polyethylenes were produced at ambient conditions.

关 键 词：Olefin polymerization PHOTOCHEMISTRY Polyethylene Polar monomer Nickel catalyst 

分 类 号：O64[理学—物理化学]