Study On Surface Modificayion Of Nano-Silica

Silica is a very important material in industry. It is usually used as reinforcing agents in rubber, ceramics and other materials. The silica was non-toxic and tasteless, and it has a well compatibility with body, so it was used as a carrier of drug and proteins.There are two methods for preparing the silica in industry: precipitation and gas phase method. The precipitated silica needs to be calcinated because there is a large number of crystal water in surface. It will cause energy waste and bad dispersion. The fumed silica has a good performance, but the technology and equipment is complicated, otherwise the HCl gas in reaction has a strong corrosive, it will pollute the environment. Therefore, there is still room for improvement in the preparation of silica.Through hydrothermal method, we prepare silica with sodium silicateand sulfuric acid. It has advantages of high condensation, a uniform particle size distribution and a good morphology, but from the SEM and laser particle size measurements, there is a partial reunion. So the silica needs surface modification for application and solving the phenomenon of agglomeration, to improve the dispersion performance and increase the compatibility with the organic material. The traditional method is to modificate silica with silane coupling agent, but the process needs to be carried out in the organic phase. The silica prepare by hydrothermal method need to be dried, it will cause agglomeration. Based on the above reasons, we want to find a solution to modificate silica in aqueous phasebeforedesiccationTo modificate the silica, we use CTAB, emulsifier-free emulsion polymerization and emulsion polymerization, then we discuss the reaction condition. After comparison, it is concluded that the effect of the emulsion polymerization method on the modification of silica is the best by using MMA as monomer. The result shows that the method significantly improves the dispersion and reach a single dispersion effect.Finally, we have an application testing. Add the modificated silica into the coating, the performance is significantly improved than the products sold in market, it achieve the expected goal.