Rheological measurements in titania gels synthesized from reverse micelles

TiO2 sol and gel systems have been synthesized by hydrolysis of titanium butoxide in microemulsions W/O. Different systems compositions were prepared at constant Wo=[H2O]/[AOT] and changing R=[H2O]/[Ti(BuO)4]. Experimental measurements show a progressive increase of the viscosity with time, characteristic of a sol–gel transition. The rheology of the transition was studied by following the behavior of viscoelastic parameters (G′, G″ and η*) as a function of time at different frequencies. The possibility to apply standard percolation theory was discussed. The application of two alternative growth models — either `fractal growth modelʹ or `nearly linear growth modelʹ — has been analysed.