Hydrocarbon dispersion of nanospherical silica by a sol-gel process. 1. Tetraethoxysilane homopolymerization

This study focused on the preparation of a hydrocarbon dispersion of nanosp herical silica using tetraethoxysilane homopolymerization by a sol-gel proc ess catalyzed by NH4OH in ethanol. The silica surface was rendered hydropho bic by the introduction of trimethylchlorosilane or trimethylethoxysilane a s a terminator. Organophilic particles with diameters in the range 10-130 n m were obtained under controlled conditions. Nevertheless, the organophilic fraction dispersed in hexane was not greater than 62%. The homopolymerizat ion reaction time was directly related to the particle size and, in some ca ses, its insolubility. High terminator concentration and low termination te mperature favored the increase in the number of organophilic particles. The chlorine-containing terminator was more efficient in promoting the product ion of hydrocarbon hydrophobic nanospheres.