摘要
For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sandwich"type turned out to be an eficient category in achieving high molecular weight polyolefin.In the a-dimine system,the"sandwich"type catalysts were built using the typical 8-aryl-naphthyI framework.In this contribution,by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings,a new class of "sandwich-like"a-diimine nickel catalysts was constructed and fully identified.The rotationally restrained benzosuberyl substituents played a"sandwich-like"function by capping the nickel center from two axial sites.Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent,Ni2 featuring benzosubery|substituent enabled the increase(8 times)of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene.By further increasing the steric bulk of another ortho-site of the N-aryl ring,the polymer molecular weight even reached an ultrahigh level of 833 kDa(Mw=1857 kDa)using the optimized Ni3.Notably,these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate,with Ni3 giving the highest copolymer molecular weight(88 kDa)and the highest incorporation of comonmer(2.0 mol1%),along with high activity of up to 10^(5)g·mol^(-1)·h^(-1).
基金
the National Natural Science Foundation of China(Nos.21871250 and 22001244)
the Jilin Provincial Science and Technology Department Program(No.20200801009GH).
作者简介
Corresponding authors:Yue Chi,E-mail:yuechi@ccut.edu.cn;Corresponding authors:Yi-Xin Zhang,E-mail:zhangyixin@ciac.ac.cn;Corresponding authors:Zhong-Bao Jian,E-mail:zbjian@ciac.ac.cn。
