SURFACE-MORPHOLOGY OF SILICA FILMS DERIVE D BY THE SOL-GEL METHOD ANDITS APPLICATION TO A WATER REPELLENT GLASS

Silica films with various surface morphologies, such as flatness, meso porosity, uneveness, convexity, were prepared by hydrolysis and polyme rization of tetraethoxysilane, Si(OC2H5)(4)(TEOS) and methyltrietoxysi lane, CH3Si(OC2H5)(3)(MTES) under acid-catalyzed conditions, The morph ology of coatings could be changed by changing the molar ratio (denote d as f,f=MTES/TEOS) in TEOS-MTES mixture, as well as the conditions of drying process and heat treatment temperature, Especially, in the cas e of 5<f less than or equal to 7.5, the surface of coatings was uneven , when films were prepared at humidities higher than 45 RH%. Water rep ellent glasses obtained by coating hydrolyzed heptadecafluorodecyltrim ethoxysilane, CF3(CF2)(7)CH2CH2Si(OCH3)(3) on to this uneven surface s howed an excellent abrasion resistance and W-light stability for windo ws of automobiles and buildings.