氨基甲酰基季铵盐双功能催化剂催化丙交酯开环聚合研究  

Ring-opening Polymerization of Lactide by Bifunctional Organocatalyst at Ambient Conditions

作　　者：李海强 汪婧怡 武莉 刘威 程瑞华[1] 刘柏平[1,2] Hai-qiang Li;Jing-yi Wang;Li Wu;Wei Liu;Rui-hua Cheng;Bo-ping Liu(State Key Laboratory of Chemical Engineering,East China University of Science and Technology,Shanghai 200237;College of Materials and Energy,South China Agricultural University,Guangzhou 510642)

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237 [2]华南农业大学材料与能源学院,广州510642

出　　处：《高分子学报》2019年第12期1290-1297,共8页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21576086)资助项目

摘　　要：采用3种氨基甲酰基季铵盐双功能有机小分子催化剂考察了丙交酯的溶液聚合与本体聚合.催化剂由二甲酰亚胺和季铵盐在回流条件下以定量收率制备,原料廉价易得,在空气中性质稳定且毒性低,可在温和无惰性气体保护条件下催化丙交酯的开环聚合.在以甲苯为溶剂的聚合条件下,a催化剂(2-氨基甲酰基苯甲酸四乙基铵)常温常压下反应1 h,丙交酯转化率为42.7%.由正交法得出的最佳聚合条件下,丙交酯/a催化剂/叔丁醇钠的摩尔比为200/10/1,75℃,反应4 h后,丙交酯转化率为88.5%,产物聚乳酸的分子量为8.03 kg·mol^-1.采用本体聚合的方法,3种催化剂均可在无引发剂的条件下合成聚乳酸.通过调控引发剂、金属醇盐及温度条件合成的聚乳酸,在150℃下丙交酯转化率达95.7%.几种方式所得产物熔融温度在130~134℃之间.产物经MALDI-TOF-MS表征,证实氨基甲酰基季铵盐催化剂具有协同双重活化单体和引发剂/链端的性能,双功能团位于同一结构中.Ring-opening polymerization of lactide(LA) is one of the most important techniques to synthesize poly(lactic acid)(PLA). In this work, a series of organocatalysts have been prepared for both solution polymerization and bulk polymerization of LA at ambient conditions. Derived from the facile reactions between phthalimide and quaternaryammonium salt, these catalysts are inexpensive and stable in air. Tetraethylammonium2-aminobenzoate(TEACB)(catalyst a) was first applied to polymerize LLA in toluene solvent, and a conversion of 42.7% was achieved after the reaction proceeded at 25 ℃ for 1 h. Orthogonal experiments suggested that the optimum condition was reaction temperature of 75 ℃, reaction time of 4 h, and the molar ratio of lactide:catalyst a:alkoxide equal to 200:10:1, which afforded PLA product with molecular weight of 8.03 kg·mol–1, polydispersity index(PDI) of 1.53, and a high conversion of 88.5%. Next, bulk polymerization of LLA was carried out at different temperatures to explore the effects of initiator, alcohol salt, reaction time, and the molar ratio of lactide:catalyst:alkoxide. The catalytic activity of the catalysts depended largely on their chemical structures.Under the same reaction temperature, catalyst b with larger cation part led to a higher conversion;meanwhile,catalysts a and b with phenyl group in the anionic part were more active than catalyst c bearing an aliphatic group although the latter produced PLA with higher molecular weight and narrower molecular weight distribution. The catalysts developed in this study worked well in the absence of alkoxide, whilst alkoxide and alcohol could improve the performance of the catalyst system. LLA polymerizations could be conveniently performed under atmospheric conditions and increasing temperature resulted in PLA products with higher molecular weight and narrower molecular weight distribution. The conversion reached up to 95.7% after polymerization at 150 ℃, in which the Mn and PDI of the PLA product equaled 2.57 kg·mol^–1 and 1.24, resp

关 键 词：丙交酯 双功能有机小分子催化剂 开环聚合 聚乳酸 

分 类 号：TQ323.4[化学工程—合成树脂塑料工业]