A COMPARATIVE-STUDY OF SURFACE FRACTALITY BETWEEN POLYMERIC AND PARTICULATE TITANIA AEROGELS

The surface fractality was studied for polymeric and particulate titan ia aerogels prepared via CO2 supercritical drying of titania lyogels. The surface fractal dimensions of these mesoporous aerogels were deter mined from their nitrogen adsorption isotherms by means of the Frenkel -Halsey-Hill method and the thermodynamic method. The results from the se distinctly different methods have been found to be similar; the fra ctal 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 mi croscopy, can be attributed to the difference between the proposed mec hanisms for formation of polymeric and particulate lyogels. (C) 1998 A cademic Press.