Preparation and characterization of modified SiO2 nanospheres with dichlorodimethylsilane and phenyltrimethoxysilane

In this study we synthesized spherical nanosilica by the Sol-Gel method using tetraethyl orthosilicate (TEOS), and the average particle diameter was measured by scanning electron microscopy (SEM). The surface of silica nanoparticles was modified with two kinds of silane coupling agents: dichlorodimethylsilane (DCDMS) and phenyltrimethoxysilane (PhTMS). We investigated the effect of the type of silane coupling agent with different functional groups (alkoxy or chloro) on the surface properties of modified silica by various analytical methods, i.e., FT-IR spectroscopy, CHN analysis, UV-visible spectra and thermogravimetric analysis (TGA) measurements. The particles modified with DCDMS showed larger grafting density from CHN analysis and higher weight loss from TGA measurement indicating the higher content of silane grafted on the surface of SiO2 nanoparticles. We suggest that the variations in grafting were dependent on the silane condensation which indicating the greater ability of condensation reaction of DCDMS with OH groups of silica rather than PhTMS.