二氧化硅微球的制备与形成机理

在酯-醇-水-碱体系中以正硅酸乙酯为硅源、氨水为催化剂、乙醇为溶剂,采用改进的溶胶-凝胶法合成了二氧化硅球形颗粒。采用红外光谱、BET吸附曲线、扫描电镜等手段重点研究了正硅酸乙酯加料方式对二氧化硅粒径和形貌的影响。分析表明,采用正硅酸乙酯分步滴定法能提高二氧化硅微球的球形度、窄分布、单分散与致密性。同时,在反应温度25℃、正硅酸乙酯浓度0.12mol/L、氨浓度为15.0mol/L、去离子水浓度0.90mol/L、无水乙醇浓度2.35mol/L、pH值为9～12的条件下,获得了直径约200～250nm、粒径一致性约为0.5、分布偏差约为7.5%的球形二氧化硅单分散颗粒;研究和讨论了二氧化硅微球的形成机理。

Synthesis and Formation Mechanisms of Silicon Dioxide Spherical Particles

The monodispersed silicon dioxide spherical particles were synthesized by sol-gel methods,tetraethoxysilane(TEOS) as silicon material,ammonia as catalyst and ethanol as solution in ester-alcohol-water system. In order to illuminate TEOS titration modes,reactant concentration and reaction temperature effects on size and morphology of SiO2,samples are tested by SEM,BET and FT-IR. The results show that TEOS titration step by step is propitious to round, monodisperse and compact SiO2 synthesis. Under condition of reaction temperature of 25 ℃,TEOS moore concentration of 0.12 mol/L,ammonia of 14.8 mol/L,deionized water,and the pH value controled between 9～12,monodispersed silica spheres 200～250 nm in diameter,diametical consistency about 0.5 and standard deviation 7.5% were obtained. The formation mechanisms of SiO2 under different reaction conditions were also discussed.