稀土三元/TMAF体系催化二氧化碳与环氧丙烷交替共聚及机理研究  

Alternating Copolymerization and Theoretical Study on CO_2 and Propylene Oxide over Ternary Rare Earth Metal/TMAF Complexes

作　　者：孟庆洋[1] 程瑞华[1] 侯侨丽 潘星[1] 刘柏平[1] 李佳佳[1] MENG Qing-yang CHENG Rui-hua HOU Qiao-li PAN Xing LIU Bo-ping LI Jia-jia(State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, Chin)

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

出　　处：《功能高分子学报》2016年第4期424-431,共8页Journal of Functional Polymers

基　　金：上海市浦江人才计划(16PJD016)

摘　　要：在稀土三元催化体系（三氯乙酸钇-二乙基锌-甘油）中加入相转移剂四甲基氟化铵（TMAF）,并用于催化二氧化碳和环氧丙烷交替共聚。采用核磁共振（^1H-NMR）、凝胶渗透色谱（GPC）、差示扫描量热（DSC）、热重分析（TG）和原位傅里叶转换红外光谱（in situ FT-IR）等对聚合过程和产物结构性能进行表征分析。采用基于密度泛函理论（DFT）的分子模拟方法对聚合起始步骤链增长机理进行探究。研究结果表明：稀土三元/TMAF催化体系可以在不改变聚合特征和共聚物结构性能的情况下,得到高达4 740.6g/mol（1mol Zn催化得到聚合物的质量）的催化活性,且将催化剂诱导期从100min缩短至20min。机理研究表明：环氧丙烷的插入步骤为反应的速控步骤,且该步骤所需克服的吉布斯自由能能垒随模型催化剂活性锌中心的自然成键轨道电荷的增加而降低,环状链增长机理中二氧化碳的插入并“返咬”成环所需克服的吉布斯自由能能垒很高,进一步证实了二氧化碳和环氧丙烷共聚反应更倾向于遵循链状链增长聚合机理形成聚碳酸亚丙酯。The copolymerization behavior of CO2 and propylene oxide （ PO ） over ternary rare earth metal complex （ ZnEt2-Y （ CCI 3 COO ）3-glycerine/tetramethylammonium fluoride （ TMAF ）） were investigated systematically. The copolymerization process and chemical properties were characterized by 1 H-Nuclear Magnetic Resonance^1 H-NMR）,Gel Permeation Chromatography（GPC）,Differential Scanning Calorimetry （DSC）,Thermal Gravity （TG） and in-situ Fourier Transform Infrared Spectrometer （in situ FT-IR）. The initial step of C0 2 and PO insertion was calculated by Density Functional Theory（DFT） method. Results showed that the application of TMAF in ZnEt 2- Y （ CCl3 COO ） 3-glycerine catalyst dramatically increased the catalytic activity up to 4 740. 6 g / mol （ mass of polymer for 1 mol Zn） and decreased the catalytic inductionperiod from 100 min to 20 min. The theoretical results demonstrated that the rate-determining step of C0 2 and PO copolymerization was the ring-opening/insertion period of PO. The Gibbs free energy of the rate-determining step decreased with the increase of natural bonding orbital of the zinc metal center. In addition,the Gibbs free energy of CO2 insertion to form “back-bite” cyclic chain growth structure was high. Thus,the copolymerization of CO2 and PO might follow the linear chain growth mechanism to obtain poly（propylene carbonate）.

关 键 词：二氧化碳 环氧丙烷 相转移剂 稀土三元催化剂 交替共聚机理 

分 类 号：O623[理学—有机化学] O662[理学—化学]