SiO_2单分散溶胶微球制备的工艺条件研究

Synthesis of Monodisperse Colloidal Silica Particles by Hydrolysis of Metal Alkoxide

在乙醇介质中,以氨作为催化剂,正硅酸乙酯作为硅源,制备了单分散的二氧化硅溶胶微球。通过激光粒度分析仪及透射电镜测定溶胶粒子的大小。研究了不同工艺参数如催化剂和水的量、硅源的量以及溶剂的类型对二氧化硅粒子大小及形貌的影响,并考察了粒子的形成机理。结果显示:随着氨浓度的升高,溶液初始解离的[OH-]增大,二氧化硅粒子的粒径增大;随着硅源浓度的增加,溶液中水解的中间产物增加,二氧化硅微球的粒径显著增加;在r(水/正硅酸乙酯)值远大于4的情况下,随着初始加入水量的增加,二氧化硅微球的粒径有所增加,但当水量太多时,粒径反而下降;使用不同溶剂作为制备二氧化硅的介质,在丙醇和丁醇中二氧化硅严重团聚,没有得到单分散微球。

Monodisperse colloidal silica particles were obtained in the ethanol medium in the presence of TEOS as silicon source and ammonia as catalyst. Transmission electron microscope and laser scattering particle analyzer were used to determine the average particle size. The effects of the amount of ammonia and water, the concentration of TEOS and the type of solvents on particle sizes were investigated. The formation mechanisms of the SiO2 particles under these conditions were also studied and discussed. The results show that with the concentration of ammonia increased, the particle size increased due to the increase of [ OH^- ]. The increase of the concentration of TEOS affected the diameter of the SiO2 particles apparently. When the ratio of water to TEOS Overwhelmed 4 ultimately, the increase of water amount can have different consequence to the diameter of particles. In the propanol and butanol solvent system, monodispersed particles were not obtained due to the agglomeration.