Modification Of Nanosize Silica And Preparation Of Nano-composites

In this paper, nano-silica was prepared via sol-gel technology. The surface of nanosize silica was modified by oleic acid and silane coupling agent respectively. Then using nanosize silica colloid modified by silane coupling agent as seed, nano-SiO2/polymer composite emulsion was synthesized.First, nano-silica spherical particles have been prepared by hydrolysis of tetraethoxy silane (TEOS) in alcohol-water mixed solvent, which is catalyzed by ammonia. Effects of the amount of water in alcohol, the concentration of ammonia and TEOS and temperature of hydrolysis on the particle sizes of SiO2 were studied.The surface modification of nanosize silica prepared was performed by oleic acid, which aimed to improve the compatibility between nanosize silica and organic phase. Second, nano-silica sol was modified by silane coupling agent KH-570. The chemical reaction between nano-silica and KH-570 was proved by infrared spectrum analysis and elemental analysis. Then using the modified silica as seed, a seeded emulsion polymerization was carried out to prepare composite polymer emulsion by adding styrene (St). Effects of polymerization processe parameters on the property of the composite emulsion were studied such as SDS concentration and adding style of monomer. The chemical reactions between modified silica surfaces and polymer were characterized by infrared spectrum (IR) analysis and the core-shell morphology of latex particles was proved by transmission electron microscope (TEM) .