A disubstituted-norbornene-based comonomer strategy to address polar monomer problem  

一种基于二取代极性降冰片烯的策略用于解决极性单体共聚问题

作　　者：Menghe Xu Changle Chen 徐梦贺;陈昶乐(Key Laboratory of Soft Matter Chemistry,Department of Polymer Science and Engineering,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]Key Laboratory of Soft Matter Chemistry,Department of Polymer Science and Engineering,University of Science and Technology of China,Hefei 230026,China

出　　处：《Science Bulletin》2021年第14期1429-1436,M0004,共9页科学通报（英文版）

基　　金：the National Natural Science Foundation of China(52025031,21690071,U19B6001,and U1904212);K.C.Wong Education Foundation。

摘　　要：The transition-metal-catalyzed copolymerization of olefins with polar comonomers is a direct strategy to access polar-functionalized polyolefins in an economical manner.Due to the intrinsic poisoning effect of polar groups towards Lewis acidic metal centers and the drastic reactivity differences of polar comonomers versus non-polar olefins,it is challenging to develop catalysts that provide the desired polymer molecular weight,comonomer incorporation,and activity.In this contribution,we tackle this issue from a comonomer perspective using 5,6-disubstituted norbornenes,which are highly versatile,easily accessible,inexpensive,and capable of introducing two functional groups in a single insertion.More importantly,they are only mildly poisoning due to the presence of long spacers between double bonds and polar groups,and are not prone to b-hydride elimination due to their cyclic structures.As strong pdonors,they can competitively bind to metal centers versus olefins.Indeed,phosphine-sulfonate palladium catalysts can catalyze the copolymerization of ethylene with 5,6-disubstituted norbornenes and simultaneously achieve a high polymerization activity,copolymer molecular weight,and comonomer incorporation.The practicality of this system was demonstrated by studying the properties of the resulting polymers,copolymerization in hydrocarbon solvents or in bulk,recovery/utilization of unreacted comonomer,molecular weight modulation,and large-scale synthesis.过渡金属催化烯烃与极性单体的共聚反应是制备功能化聚烯烃最直接的途径.极性官能团对金属中心的毒化和极性单体与非极性烯烃之间反应活性的差异使得高性能催化剂的开发依然具有很大的挑战性.本文从共聚单体的角度出发,使用廉价、易得的5,6-二取代降冰片烯类单体与乙烯进行共聚,并且该单体能够在此过程中能够一次性插入2个极性官能团.更为重要的是,此类环状单体的优势在于其对金属中心较弱的毒化,同时也不易于发生β-氢消除反应.此外,π键的强供电子效应使得此类单体能够与乙烯形成有利的竞争配位.采用膦磺酸钯催化剂催化乙烯与5,6-二取代降冰片烯的共聚反应,进而制备出具有高活性、高聚合物分子量和高极性单体插入比的共聚物.在此过程中,还研究了工业溶剂的使用、极性单体本体中的共聚、极性单体的回收与再利用、共聚物分子量的调控、规模化的合成以及共聚物的性质等.

关 键 词：Olefin polymerization POLYOLEFIN Palladium NORBORNENE Polar monomer 

分 类 号：TQ317[化学工程—高聚物工业]