Highly Cis-1,4 Selective Polymerization of Conjugated Dienes Catalyzed by ^-heterocyclic Carbene-ligated Neodymium Complexes  

作　　者：Shu Zhang Na Wu Yi-Xian Wu 

机构地区：[1]State Key Laboratory of Chemical Resource Engineering,Beijing Advanced Innovation Center for Soft Matter Science and Engineering,Beijing University of Chemical Technology,Beijing 100029,China

出　　处：《Chinese Journal of Polymer Science》2020年第12期1305-1312,共8页高分子科学（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.21634002);the Fundamental Research Funds for the Central Universities(Nos.XK1802-2 and XK1802-1).

摘　　要：Neodymium complexes containing N heterocyclic carbene(NHC)ligands,NdCl5[1,3,R(NCH=)2C]-THF,(Nd1:R=2,6-Pr2C6H3,x=0;Nd2:R=2,6-Et2C6H3,x=1;Nd3:R=2.4,6-Me3C6H2,x=1)were synthesized and employed as precatalysts for the coordination polymerization of conjugated dienes(butadiene and isoprene).In combination with trisobutylaluminium(TIBA),Nd1 promoted butadiene polymerization to produce extremely high cis-1,4(up to 99.0%)polybutadienes with high molecular weight(Mw=250-780 kg·mol 1).The Nd1/TIBA catalytic system also exhibited both high catalytic activity and cis-1,4 selectivity(up to 97.8%)for isoprene polymerization.The catalytic activity,molecular weight and molecular weight distribution of resulting polydienes were directly influenced by Al/Nd molar ratio,aging method,and polymerization temperature.Very interestingly,the high cis-1,4 selectivity of the catalyst towards butadiene and isoprene kept almost unchanged under different reaction conditions.The cis-1,4 polyisoprenes with high molecular weight(Mw=210-530 kg·mol 1)and narrow molecular weight distribution (Mw/Mn=1.9-2.7)as well as high cis-1.4 selectivity(-~97%)could be synthesized by using the aged Nd1/TIBA catalytic system in the presence of isoprene(100 equivalent to Nd)at low AlNd molar ratios of 6-10.Polyisoprenes with low molecular weights(Mw=12-76 kg·mol-7)and narrow molecular weight distributions (Mw/Mn=1.7-2.6)were obtained by using Nd2 and Nd3 as precatalysts,indicating that the molecular weight of resulting polyisoprenes can be adjusted by changing the substitutes of ligand in Nd complex.

关 键 词：Neodymium complex N heterocydic carbene igand Coordination polymerization Cis-14 sletivity Aging method 

分 类 号：TQ316.3[化学工程—高聚物工业] TQ426