Rheological Measurements in titania gels synthesized from reverse micelles

S. D. ROMANO; D. H. KURLAT

CHEMICAL PHYSICS LETTERS

Elsevier

Lugar: Oxfordshire, Inglaterra; Año: 2000 vol. 323 p. 93 - 97

0009-2614

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 h*) as a function of time at different frequencies. The gelification point  was determinated at the crossing – point of G´ and G´´, at the lowest frequency. The possibility to apply standard percolation theory was discussed. The application of two alternative growth models -either “fractal growth model” or “nearly linear growth model”- has been analysed.