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3-Methacryloxypropylpolysilsesquioxane (MA-PS) was prepared by acid-or base-catalyzed hydrolytic polycondensation of 3-methacryloxypropyltrimethoxysilane (MAS). MA-PS coating film was prepared by dip-coating on organic, metal and inorganic substrates, including poly(-ethylene terephthalate), aluminum, stainless steel, and glass. The coating films on poly(ethylene terephthalate) and glass showed high adhesive strength. The hardness of coating films increased with increasing heat treatment temperature, whereas they decreased with increasing H 2 O/MAS molar ratio. The refractive index of coating films increased with increasing heat treatment temperature. In addition, flat and transparent free-standing films (0.24-0.27 mm thickness) were prepared from MA-PS that were crack-free after heat treatment at 1000°C.

Polyvinylpolysilsesquioxane (PVPS) organic-inorganic hybrid gel films comprising polyethylene and siloxane backbone linkages were prepared through two routes: trimethoxy(vinyl)silane (VTS) was first subjected to radical polymerization of the vinyl groups, followed by acid-catalyzed hydrolytic polycondensation of the trimethoxysilyl groups (route A) to afford PVPS; in the second route PVPS was prepared in reverse order (route B). PVPS gel films were transparent and homogeneous. We find that the mechanical and heat-resisting properties correlate both to the degree of polymerization and the degree of cross-linking.

The reaction of 4-vinyl-1-cylcohexene with [HMe 2 SiOSiO 1.5 ] 8 provides tetra-and octa-2cyclohexenylethyloctasilsesquioxanes. The tetrabifunctional [cyclohexenylethylMe 2 SiOSiO 1.5 ] 4-[HMe 2 SiOSiO 1.5 ] 4 (average degree of functionalization) melts near 80 • C and can be cast and then cured (by thermal hydrosilylation) into transparent nanocomposite shapes. These materials, while not nanoporous, offer dielectric constants of 2.8-2.9 at 100 kHz to 3 MHz, and are air stable to temperatures ≥400 • C. The resulting materials appear (by X-ray diffraction) to be partially ordered after curing. The octafunctional material also melts at low temperatures (ca 120 • C) and can be copolymerized with hydridosiloxanes to give similar materials with lower thermal stability. The synthesis and characterization of the starting materials is described, as well as thermal curing studies and properties characterization of the resultant nanocomposites.

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