Horizontally and Vertically Concerted Steric Strategy inα-Diimine Nickel Promoted Ethylene(Co)Polymerization  

作　　者：Xiaoqiang Hu Yixin Zhang Baixiang Li 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》2021年第10期2829-2836,共8页中国化学（英文版）

基　　金：support from the National Natural Science Foundation of China(Nos.21871250 for Z.Jian,22001244 for Y.Zhang);the Jilin Provincial Science and Technology Department Program(No.20200801009GH).

摘　　要：Main observation and conclusion Steric bulk plays a significantly paramount role in late transition metal promoted olefin(co)polymerization in terms of polymer molecular weight and catalyst thermal stability.Numerous sterically encumbered nickel and palladium catalysts have been developed,but they are usually uni-directional.In this contribution,from a bi-directional side the distinctive horizontally and vertically concerted steric strategy was well-developed and applied toα-diimine nickel catalysts.In ethylene polymerization,the increase of vertically steric bulk(H,Ph,Biph)led to an enhanced polymer molecular weight,a slightly ascended branching density;likewise increasing horizontally steric bulk(Ph,Nap,Ant)further resulted in the increase of polymer molecular weight and branching density.As a result,in sharp contrast to Ni1(H)without steric bulk,Ni5(Ant)with horizontally and vertically concerted steric bulk was thermally stable,showed very high activities at a level of 107 g·mol–1·h^(–1),and produced polyethylenes with the highest molecular weight of 518.8×10^(4)g·mol^(-1)and the broader range of branching density from 2.4/1000C to 27.8/1000C.In the copolymerization of ethylene with methyl 10-undecenoate,Ni5(Ant)also provided the highest copolymer molecular weight but gave the lowest incorporation of co-monomer.This work sheds light on the steric effect on olefin(co)polymerization.

关 键 词：Olefin polymerization Steric effect Homogeneous catalysis UHMWPE NICKEL 

分 类 号：O64[理学—物理化学]