正丁基锂-丁二烯-1,2-二甲氧基乙烷阴离子聚合体系的动力学研究

Kinetics of Anionic Solution Polymerization of n-BuLi-Butadiene-Dimethoxyethane System

以1,2-二甲氧基乙烷为溶剂,以正丁基锂为引发剂,在充氮条件下,利用膨胀计进行了丁二烯聚合增长反应动力学研究。结果表明,增长反应对单体浓度和活性种浓度的反应级数皆为一级关系,活化能为24.79kJ/mol,频率因子为1.54×10~6L·mol^(-1)·min^(-1);并求出生成1,4-和1,2-结构含量的分速度常数分别为k_3=2.15×10_e^6^(-6900/RT)L·mol^(-1)·min^(-1),k_4=2.45×10_e^5^(-5000/RT)L·mol^(-1)·min^(-1)。同时求出在1,2-二甲氧基乙烷溶剂中1,2-结构含量与温度的经验关系式为a=79.67-0.222t,指数关系式为a=0.159_e^(930/RT)。此外,对活化能E和溶剂极性的过渡态能E_T之间的关系式作了实验论证。

The kinetics of anionic polymerization of butadiene in dimethoxyethane initiated by n-BuLi was studied. It is found that the propagation reaction rate is the first order with respect to the monomer and initiator concentrations, the activation energy (E) is 24.79 kJ/mol, and the frequency factor (A) is 1.54×10~6L·mol^(-1)·min^(-1). Based on the butadiene polymerization mechanism proposed by Jin Guantai and Li Tianhu, the activation energies of the corresponding reaction rate constants for forming 1, 4- and 1, 2-structurcs and their frequeney factors were also obtained, i.e.,E_(1,4)=28.84 kJ/mol, A_(1,4)=2.15×10~6L·mol^(-1)·min^(-1); E_(1,2)=20.90kJ/mol, A_(1,2)=2.45×10~5L·mol^(-1)·min^(-1).