ゾルゲル無機─有機ハイブリッド微粒子の作製とミクロ周期配列

抄録

Preparation of monodisperse inorganic-organic hybrid particles and their periodic arrangement on substrates are very attractive research topics in recent years. In this study, phenylsilsesquioxane (PhSiO_3/2) and phenylsilsesquioxane-titania (PhSiO_3/2-TiO₂) particles were synthesized by the solgel process from phenyltriethoxysilane and titanium tetra-n-butoxide. Monodisperse, spherical PhSiO_3/2 and PhSiO_3/2-TiO₂ particles were obtainable by varying the mole ratios of ethanol as solivent, hydrochloric acid for hydrolysis and ammonia water for polycondensation. PhSiO_3/2 particles softened and sintered by a heat treatment at higher temperatures than the glass transition temperature at around 150℃ . FT-IR spectra showed that PhSiO_3/2 and TiO₂ components were homogeneously hybridized in the PhSiO_3/2-TiO₂ particles through Si-O-Ti bonds. The refractive index of the particles was monotonically increased from 1.57 to 1.62 with an increase in TiO₂ content. The PhSiO_3/2-TiO₂ particles were electrophoretically deposited on indium tin oxide (ITO)-coated glass substrates to form opaque, thick films. The deposited 95PhSiO_3/2·5TiO₂ films became transparent with a heat treatment at 400℃ because of the thermal sintering of the particles.

Pregrooved substrates were useful to linearly array the monodisperse particles on the pregrooves in a short time, which was achieved by the ascending liquid flow on the substrate and the attractive capillary force between the particles. SiO₂ microparticles were successfully closed-packed by sandwiching the colloidal suspension between the barriers using a newly developed setup for particle arrangement. PhSiO_3/2 particles were selectively deposited onto the hydrophilic areas of the hydrophobic-hydrophilic patterned ITO substrates by electrophoresis. The films composed of aggregates of PhSiO_3/2 particles became transparent with morphological changes from aggregates of particles to a continuous phase after a heat treatment. After the heat treatment at 200℃ , convexly shaped PhSiO_3/2 micropatterns were formed on the hydrophilic region of the pattern. These patterning techniques have a wide variety of applications such as fabrication of micro-optical components.