FORMATION AND GELATION OF TITANIA NANOPARTICLES FROM AOT REVERSE MICELLES

Titania nanoparticles have been produced by the controlled hydrolysis of tetraisopropyltitanate (TPT) in sodium bis(2-ethylhexyl)sulfosuccin ate (AOT) reverse micelles. Particle formation and aggregation were in vestigated by static and dynamic light scattering and the chemical spe cies by vibrational spectroscopy. The kinetics of particle formation a nd aggregation were controlled by varying [H2O]/[AOT] (w(0)), [H2O]/[T i(IV)] and [AOT]/[Ti(IV)]. Nanoparticles, with diameters <10 nm, could be produced at relatively high Ti(IV) concentrations (up to 0.05 M). These nanoparticles aggregated into sols, with colloid sizes of 20 to 200 nm, eventually forming gelatinous precipitates. Different titania phases were produced, depending on the size of the micellar water pool ; small pools (w(0) < 6) yielded amorphous particles, while larger poo ls (w(0) > 10) produced anatase.