文献类型：期刊文献

英文题名：Highly Isoselective and Active Zinc Catalysts for rac-Lactide Polymerization: Effect of Pendant Groups of Aminophenolate Ligands

作者：Kan, Chao;Hu, Jianwen;Huang, Yang;Wang, Haobing[1];Ma, Haiyan[1]

机构：[1]East China Univ Sci & Technol, Shanghai Key Lab Funct Mat Chem, Sch Chem & Mol Engn, Shanghai 200237, Peoples R China; East China Univ Sci & Technol, Lab Organometall Chem, Sch Chem & Mol Engn, Shanghai 200237, Peoples R China

年份：2017

卷号：50

期号：20

起止页码：7911

外文期刊名：MACROMOLECULES

收录：;EI(收录号：20174304310869);WOS:【SCI-EXPANDED(收录号:WOS:000413885100010)】；

基金：This work is subsidized by the National Natural Science Foundation of China (NNSFC, 21474028) and the Fundamental Research Funds for the Central Universities (WD1113011). All the financial support is gratefully acknowledged. H. Ma also thanks the very kind donation of a Braun glovebox by the AvH Foundation.

语种：英文

外文关键词：Zinc compounds - Dihedral angle - Biographies - Catalyst activity - Ring opening polymerization

摘要：Highly isoselective and active ring-opening polymerization of rac-lactide to obtain stereocomplexed polylactide is a long-standing challenge. In this contribution, zinc catalysts with good isoselectivities and high activities (P-m = 0.87, TOF = 3312 h(-1) at 25 degrees C; P-m = 0.92, TOF = 117 h(-1) at -20 degrees C, toluene) for rac-lactide polymerization are reported. These catalysts are coordinated by a well-designed. chiral oxazolinyl or achiral benzoxazolyl aminophenolate ligand. Both types of zinc complexes afforded multiblock isotactic PLAs, proving to be formed via a chain-end control mechanism regardless of the existence of a chiral group or not. Preliminary studies suggested that the dihedral angle between the phenoxy and oxazolinyl/benzoxazolyl planes in these complexes reflects the steric bulkiness of the ligand and has a close relation with the isoselectivity of the complex, which might serve as a guide in obtaining new,isoselective catalysts of similar types. Furthermore, unprecedented combination of excellent activity (TOF up to 44 000 h(-1)) and sufficient isoselectivity (P-m = 0.80) could be achieved under solvent-free immortal conditions with catalyst loadings as low as 0.005 % (vs monomer); which shows the potential of industrial application.