Abstract
Hollow silica nanospheres were prepared through the sol-gel process of silicon tetramethoxide in reverse liquid-liquid dispersions. Sorbitan trioleate and/or sodium bis(2-ethylhexyl)sulfosuccinate (AOT) were dissolved at 10 wt% in cyclohexane to prepare an oil phase. Citric acid aqueous solution at a pH of 5.0 was used as an aqueous phase. When the aqueous phase at a volume fraction of 0.01 was mixed with the oil phase at AOT concentrations of 60 mass% and less, reverse emulsions were formed. The products were more than 200 nm in size with wide size distribution. The solubilization was observed at AOT concentrations of 70 mass% and more. The products were recognized to be hollow nanospheres, of which the size was ranged from 20 to 30 nm and the wall thickness was ca. 5 nm. Such an almost uniform size suggests that the nanospheres have been produced at the reverse micelles as the reaction site.
