Sol-Gel法二氧化硅溶胶的制备及稳定性研究

Preparation and Stability of Silica Sols Prepared by Sol-Gel Process

以正硅酸乙酯为前驱体,硝酸为催化剂,制备了二氧化硅(SiO2)溶胶。研究了催化剂、水、乙醇的加入量及反应时间、反应温度、干燥控制添加剂对溶胶稳定性的影响。结果表明,在保持其它反应条件不变的情况下,随着n(无水乙醇EtOH)/n(正硅酸乙酯TEOS)的增大,溶胶的凝胶时间变长;随着H2O/TEOS摩尔比的增大,溶胶的凝胶时间先变短后变长,水酯摩尔比Rw=9.6左右时溶胶的凝胶时间最短;pH<2时,随着Rw的增大,溶胶的凝胶时间变短;反应温度的升高及反应时间的延长,都会促使溶胶的凝胶时间变短;添加剂N,N-二甲基甲酰胺可以增加溶胶的稳定性。

Silica sols was prepared using TEOS as the precursor and HNO3 as the catalyst by sol - gel process. The effects of the amount of catalyst, water, ethanol, reaction temperature, reaction time, aging temperature and DMF on the stability of SiO2 sols were inspected during the sol - gel processing. The results showed that with the increas- ing of EtOH/TEOS molar ratio, the gelation time of sols increased. With the increasing of H2O/TEOS molar ratio, and gelation time firstly decreases and then increases. When H2O/TEOS is about 9.6, the to the minimum. With the increasing of HNO3/TEOS molar ratio, the gelation time of sols reduced when pH value is less than 2. Reaction temperature raising and reaction time increasing could reduce the gelation time. Adding the DMF can increase the stability of SiO2 sols.