The thermal softening behavior of poly (phezylsilsesquioxane) (PhSiO3/2) and poly (benzylsilsesquioxane) (BnSiO3/2) particles during heat treatment has been investigated from the results of gel permeation chro matography, thermal and structural analyses of the particles. Both PhSiO3/2 and BnSiO3/2 particles thermal ly softened, and the onset temperature of thermal sintering was about 140 and 50 for PhSiO3/2 and BnSiO3/2, respectively. The thermal sintering of the PhSiO3/2 and BnSiO3/2 particles was caused by the decrease of viscosity at temperatures higher than the glass transition temperatures. Glass transition was ob served for BnSiO3/2 in the repeated heating runs, while for PhSiO3/2 glass transition was appreciable only in the first heating run. From 29Si nuclear magnetic resonance spectra, the development of siloxane network during heat treatment was found to be more significant in PhSiO3/2 than in BnSiO3/2. The difference in the structural evolution during heat treatment makes PhSiO3/2 particles thermosetting and BnSiO3/2 ones ther moplastic.

Thick films of poly(benzylsilsesquioxane) (BnSiO 3/2 ) particles, prepared by the sol-gel process, were deposited onto indiumtin-oxide-coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO 3/2 particles were thermally softened and sintered at ϳ50°C, which was above the glass transition temperature of the particles. The films prepared by the electrophoretic sol-gel deposition consisted of aggregates of particles with diameters of 0.2-1 m and were opaque. The film shrank from 2.5 m to 1.4 m in thickness and became transparent upon sintering of the particles during heat treatment at temperatures >100°C.

Refractive index of ethylsilsesquioxane-titania hybrid films increased from 1.50 to 1.55 accompanied by a decrease in film thickness by about 30% after UV light irradiation. The contact angle for water of the films decreased from 95°to about 45°and the dynamic hardness increased with UV irradiation. These changes in physical and chemical properties of the films with UV irradiation were caused by the cleavage of silicon-carbon bonds and elimination of ethyl groups in the films due to the photocatalytic effect of the titania component. Micropatterning was successfully performed on the films coated on the substrates by UV irradiation through a photomask.

Prismatic patterns with a pitch of 30 m and a slant height of 30 m were embossed successfully in 70:30 (in mol%) methylsilsesequioxane:phenylsilsesqeioxane (MeSiO 3/2 -PhSiO 3/2 ) thick films on glass substrates by laminating an organic polymer sheet as a stamper with the patterns against the films. The embossed shape of the prismatic patterns precisely agreed with the negative shape of those of the stamper that was used. The resultant MeSiO 3/2 -PhSiO 3/2 films were transparent, and the refractive index of the films was adjusted to 1.51, to match that of the glass substrate.