高等学校化学学报

高等学校化学学报

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甲醇协助丙交酯开环聚合反应的理论研究

刘莉, 朱荣秀, 张冬菊, 刘成卜   

  1. 山东大学化学与化工学院理论化学研究所, 250100 济南
  • 收稿日期:2008-10-07 修回日期:1900-01-01 出版日期:2008-12-10 发布日期:2008-12-10
  • 通讯作者: 刘成卜

Computational Study of the Mechanisms for Methanol-assisted Ring-opening Polymerization of Lactide

LIU Li, ZHU Rong-Xiu, ZHANG Dong-Ju, LIU Cheng-Bu*   

  1. Institute of Theoretical Chemistry of Shandong University, Jinan 250100, China
  • Received:2008-10-07 Revised:1900-01-01 Online:2008-12-10 Published:2008-12-10
  • Contact: LIU Cheng-Bu

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被引次数

4

摘要： 采用密度泛函理论在B3LYP/6-31G(d,p)水平上研究了甲醇协助的丙交酯开环聚合反应, 探讨了1~3个甲醇分子参与的丙交酯聚合反应机理, 考察了溶剂化效应对聚合反应的影响. 结果表明, 甲醇协助的丙交酯开环聚合按加成-消除机理进行; 甲醇分子作为质子给体与受体通过与丙交酯形成环状氢键促进开环聚合, 随着甲醇分子数的增加, 环状氢键的张力逐渐减小, 反应能垒随之降低; 溶剂化效应对反应机理和反应势垒的影响均可忽略不计.

关键词: 丙交酯, 开环聚合, 甲醇, 反应机理, 密度泛函理论

Abstract: The stepwise addition/elimination and concerted mechanisms for the methanolysis of lactide, as a model for the initiation and propagation of ring-opening polymerization, were investigated computationally using B3LYP/6-31G(d,p) density functional theory calculations, with assistance from one, two and three methanol molecules. The results show that the extra methanol molecules acting as proton shuttles play a significant role in cyclic hydrogen-bonded clusters, and result in considerable energy savings. It is found that increasing the number of the ancillary methanol is accompanied by the reduction of the energy barrier for both stepwise and concerted mechanisms. The calculated results provide a general model that explains the mechanism of the titled reaction.

Key words: Lactide, Ring-opening polymerization, Methanol, Reaction mechanism, Density functional theory

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