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

Abstract

This study focused on the preparation of a hydrocarbon dispersion of nanospherical silica using tetraethoxysilane homopolymerization by a sol–gel process catalyzed by NH₄OH in ethanol. The silica surface was rendered hydrophobic by the introduction of trimethylchlorosilane or trimethylethoxysilane as a terminator. Organophilic particles with diameters in the range 10–130 nm were obtained under controlled conditions. Nevertheless, the organophilic fraction dispersed in hexane was not greater than 62%. The homopolymerization reaction time was directly related to the particle size and, in some cases, its insolubility. High terminator concentration and low termination temperature favored the increase in the number of organophilic particles. The chlorine-containing terminator was more efficient in promoting the production of hydrocarbon hydrophobic nanospheres.