Isoselective Ring-opening Polymerization of Racemic Lactide Catalyzed by N-heterocyclic Olefin/(Thio)urea Organocatalysts  

作　　者：Zhen-Yu Wang Guang-Qiang Xu Li Zhou Cheng-Dong Lv Ru-Lin Yang Bing-Zhe Dong Qing-Gang Wang 

机构地区：[1]Key Laboratory of Biobased Materials,Qingdao Institute of Bioenergy and Bioprocess Technology,Chinese Academy of Sciences,Qingdao 266101,China [2]Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Journal of Polymer Science》2021年第6期709-715,I0006,共8页高分子科学（英文版）

基　　金：by the National Key R&D Plan(No.2017YFC1104800);the National Natural Science Foundation of China(Nos.21901249 and 21950410529);Taishan Scholars Program of Shandong Province(No.tsqn201812112);“135”Projects Fund of CAS-QIBEBT Director Innovation Foundation and DICP&QIBEBT United Foundation(No.UN201701).

摘　　要：The isoselective ring-opening polymerization of racemic lactide was achieved by combining N-heterocyclic olefin(NHO)with mono(thio)ureas or bis(thio)ureas as catalytic systems.The polymerization process shows high stereoselectivity,controllability and reactivity,delivering multi-block isotactic polylactides with high chain-end fidelity and narrow molecular weight distributions.The enhancement of catalytic performance was observed in the following order:bisthiourea(DTU)<monothiourea(TU)<bisurea(DU)<urea(U).The highest Pm(probability of forming a meso dyad)=0.91 was observed at−70°C when using NHO/U1 catalytic system and the high stereoselectivity was attributed to chain-end control mechanism.

关 键 词：mechanism. HETEROCYCLIC polymerization 

分 类 号：TQ316.341[化学工程—高聚物工业] TQ426