镍金属催化剂对L-丙交酯的开环聚合效果分析

The effect analysis of Nickel metal catalyst in bulk Ring-openning polymerization of L-lactide

摘要:

本文合成了三种希夫碱镍金属催化剂：NiL1 (乙二胺缩香草醛Ni(Ⅱ))、NiL2 (邻苯二胺缩3,5-二叔丁基水杨醛Ni(Ⅱ))、NiL3 (1S,2S-二苯基乙二胺缩水杨醛镍)，并用IH NMR、X-ray单晶衍射等方法对新合成的催化剂NiL3进行了表征。以NiL1为催化剂通过单因素分析，选择合适的L-LA(左旋丙交酯)本体开环聚合条件，在此聚合条件下，对比不同配体结构特点的催化剂NiL1、NiL2、NiL3的催化聚合效果，结果表明：催化剂配体结构中引入供电子基团甲氧基有利于提高催化剂活性；配体结构中在金属活性中心周围增大位阻效应有利于得到分子量分布较窄的聚合产物。

Abstract:

Three kinds of Schiff base nickel metal complexes: NiL1[N,N’-Bis(2-hydroxy-3-methoxybenzaldehyde)-1,2-ethylenediamine Ni(Ⅱ)], NiL2[N,N’-Bis(3,5-di-tert-butylsalicylidene)-1,2-diaminobenzeneNi(Ⅱ)], NiL3[(1S,2S)-N,N’-Bis(salicylidene)-1,2-diphenylethylenediamine Ni(Ⅱ)] were synthesized and NiL3 was determined by 1H NMR and X-ray diffraction studies. Using NiL1 as catalyst to select the appropriate bulk ring-opening polymerization conditions of L-LA(L-lactide) by single factor analysis, comparison the catalytic polymerization effect of NiL1, NiL2 and NiL3 with different ligands structure features. Structural comparisons revealed that: electron donating methoxy in the catalyst ligand structure was propitious to improve the catalyst activity; steric effect around the metal activity centre of ligand structure was propitious to have polylactide polymers with narrow molecular weight distributions.