氨水对溶胶-凝胶法制备硅溶胶粒径及稳定性的影响

Effect of Ammonia on Particle Size and Stability of Silica Sol Prepared by Sol-Gel Method

本文以正硅酸乙酯(TEOS)为原料,在以氨水为催化剂的碱体系中,采用溶胶-凝胶法制备了二氧化硅溶胶。通过SEM-EDS、XRD、热重分析、激光粒度分析、Zeta电位等分析手段,研究了氨水的加入量对二氧化硅溶胶粒径以及稳定性的影响。研究结果表明,当pH值在11~12、氨水与TEOS的摩尔比R(n(NH_(3)·H_(2)O)∶n(TEOS))在1~10时,随着R值的增大,二氧化硅溶胶平均粒径y与R值x呈指数相关趋势,其拟合函数为y=2.22 x ^(1.79),相关性为0.96,粒径从10.17 nm(R=1)增加到142.48 nm(R=10),且胶粒的粒径分布半高宽从9.89 nm(R=1)增加到171.61 nm(R=10)。二氧化硅溶胶的稳定性则与氨水的加入量呈下抛物线趋势,其凝胶时间从684 h(R=1)下降到28 h(R=5),再上升到780 h(R=10)。

Silica sols were prepared by the sol-gel method using ethyl orthosilicate(TEOS)as raw material and ammonia as catalyst.The effect of ammonia addition on the particle size as well as the stability of silica sols were studied through SEM-EDS,XRD,thermogravimetric analysis,laser particle size analysis,Zeta potential,and other analytical means.The results show that when the pH value is in the range of 11~12 and the molar ratio of ammonia to ethyl orthosilicate R(n(NH_(3)·H_(2)O)∶n(TEOS))is in the range of 1~10,the average particle size y of silica sol is index correlated with the R value x.The fitted function is y=2.22 x ^(1.79 )with a correlation coefficient of 0.96,and the particle size increases from 10.17 nm(R=1)to 142.48 nm(R=10),and the half-height width of the particle size distribution increases from 9.89 nm(R=1)to 171.61 nm(R=10).The stability of the silica sol shows a downward parabolic trend with the addition of ammonia,with the gel time decreasing from 684 h(R=1)to 28 h(R=5)and then increasing to 780 h(R=10).