摘要
本文利用高分辨核磁共振仪（<sup>1</sup>HNMR）和凝胶色谱仪（GPC）研究正硅酸乙酯（TEOS）水解和水解产物缩聚动力学。首次得出水解速度常数和（?）Si—OEt浓度关系,并且测定出水解反应动力学级数。同时还测定了水解产物聚合过程中聚合物分子量的动态分布,发现当溶液H<sub>2</sub>O/TEOS】4时,,在聚合后期,分子量分布图上出现2个高聚物分布峰。聚合反应类型是缩聚反应,反应机理和弱酸性水溶液中硅酸相似,HCl抑制缩聚反应。
The kinetics of hydrolysis of tetraethyl orthosilicate (TEOS) and polycondensation of the hydrolyzed products were studied by means of high resolution ~1HNMR and gel permeation chromatography (GPC). An expression for the relationship between hydrolysis reaction rate constants and the concentration of(?)Si—OEt group was first deduced, and the order of hydrolysis reaction was determined. The dynamic molecular weight distribution of polymerization of the hydrolyzed products was measured. It is found that: (1) the molecular weight distribution of polymer appears to be a bi-modal molecular weight distribution in the final stage of polycondensation when H_2O/TEOS>4; (2) polymerization reactions possess the characteristics of polycondensation; (3) the mechanism is similar to the polycondensation of silicic acid in weak-acid aqueous solution and (4) the increase of HCl concentration retards the polycondensation.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1989年第3期204-209,共6页
Journal of The Chinese Ceramic Society
