Hydrocarbon dispersion of nanospherical silica by a sol–gel process. 2. Alkoxysilane copolymerization

Abstract

The preparation of hydrocarbon dispersions of nanospherical silica–silicone hybrids by copolymerization of tetraethoxysilane (TEOS) and alkylethoxysilanes such as methyltriethoxysilane (MTEOS) and dimethyldiethoxysilane using a sol–gel process was investigated. Particles completely dispersible in hexane with a diameter in the range 10–24 nm were obtained by means of TEOS and MTEOS copolymerization, using ethanol or methanol as a solvent and a terminator. The solubility of the nanospheres was shown to be dependent on the molar ratio of water to silicon, the reaction time, the terminator concentration as well as the stirring condition. The hexane-dispersible particles have hydroxyl and methyl groups on the surface. A higher conversion of organophilic silica–silicon nanoparticles was attained using trimethylchlorosilane as a terminator and a water-to-silicon molar ratio close to 9.