A Comparative Study of Surface Fractality between Polymeric and Particulate Titania Aerogels

The surface fractality was studied for polymeric and particulate titania aerogels prepared via CO2 supercritical drying of titania lyogels. The surface fractal dimensions of these mesoporous aerogels were determined from their nitrogen adsorption isotherms by means of the Frenkel-Halsey-Hill method and the thermodynamic method. The results from these distinctly different methods have been found to be similar; the fractal surfaces of particulate aerogels are slightly more irregular than those of polymeric aerogels. The difference in the surface morphology between the two types of aerogels, observed with scanning electron microscopy, can be attributed to the difference between the proposed mechanisms for formation of polymeric and particulate lyogels. Copyright 1998 Academic Press. Copyright 1998Academic Press