| Colloidal crystal has attracted an increasing interest due to its various applications in the fields such as photonic band-gap crystals, optoeletronic devices etc. The key in developing multi-dimensional self-assembled colloidal crystal is to control the colloidal particle size and its monodispersity. So far, only some polymer colloids such as PS et al and silica can be routinely prepared with the narrow size distribution required for forming self-assembled colloidal crystal. Monodisperse colloidal silica particles with uniform size and shape have wide application not only in the fields of physical chemistry dealing with dynamic behavior and stability of particle systems but also in industries including pigment, pharmacy, photographic emulsions, chemical mechanical polishing. Some nucleation and growth mechanism of monodisperse silica colloidal particles were put forward, but to this day , none of the available nucleation and growth mechanisms is able to explain all the experimental facts. In the paper, based on the plenty of the present of literatures, we carried out the following work and got some results:(1) The monodisperesed silicon dioxide colloidal particles were synthesized by sol-gel methods, TEOS as silicon material,ammonia as catalyst and ethanol as solution in ester-alcohol-water system. Controling different reaction experimental condition(the concentration of TEOS, water, ammonia and temperature), highly monodispersed silica colloidal particles were synthesized. When the concentration of ammonia and TEOS was increased, the particle sizes decreased; When the reaction temperature was increased, the particle sizes decreased; When the amount of water was increased first, after a miximum value, the particle sizes decreased.(2) To obtain large-sized, monodispersed spherical particles of silica, a seed particle growth method was attempted. It involves growth of silica particle prepared with an mixture solution of ammonia, water, and ethanol with continuous introduction of tetraethoxysilane(TEOS) in same solution during formation of monodisperse spheres. The influence of the concentration of seeds and the flow rate of TEOS on the size distribution of final particles was investigated. The formation of secondary particles during seed particle growth was suppressed via fine adjustment of reaction conditions, such as the concentration of TEOS and feeding ways, and the relations with distance of seed particles and secondary particles. (3) Particle formation in the hydrolysis and condensation of TEOS was studied with the basic catalysts Ammonia,Trimethylamine,N,N-dimethyliformamide,Urea.,Trithylamine. Spherical particles were formed for organic ammonia at catalyst concentrations of 0.1-0.5mol/Land NH3 at catalyst concentration of 0.5-1.89mol/L.Hydroysis of TEOS could be qualified by pH. The morphology of silica particles prepared with different organic ammonia was in the order Trimethylamine > Urea > Trithylamine≈N,N-dimethyliformamide, When Trimethylamine as catalysts, the concentration of Trimethylamine was increased, the particle sizes increased; When the reaction temperature was increased, the particle sizes decreased.(4) Anion electrolyte additives(ammonium salts) have been used to study the effect on the morphology and size of the monodispersed silica particles by the sol-gel process. Without additives, the particle size varied from 200nm to hundreds of nm depending on the TEOS, water, ammonia concentration and temperature. The addition of a small amount of electrolytes reduced the particle size up to about 100nm,The phenomena can be explained by conductivity and zeta potential. Among anion, F- have the highest effect while SO42- has the least effect.
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