Preparation and characterization of ultrafine TiO₂ particles in reverse micelles by hydrolysis of titanium di-ethylhexyl sulfosuccinate

We describe the synthesis and characterization of ultrafine TiO₂ particles (in both anatase as well as rutile form) produced by a chemical reaction within the aqueous core of a water-in-oil microemulsion. The microemulsion was stabilized and the Ti⁴⁺ ions provided by a functionalized surfactant derived from the commercially available Aerosol-OT, i.e., sodium bis (2-ethylhexyl) sulfosuccinate (Na-DEHSS). The Na⁺ ions in Aerosol-OT were completely replaced by Ti⁴⁺ through an ion-exchange reaction in nonaqueous solvents. Ultrafine TiO₂ particles were produced by the hydrolysis of the Ti-containing surfactant in the water droplets. The dependence of the size of the precipitated TiO₂ · xH₂O particles on various structure parameters of the microemulsion was studied in detail.