Polysilsesquioxane (PSQ) liquids have been prepared from propyltrimethoxysilane-water and trimethoxy(3-sulfanylpropyl)silane-water binary systems without the use of organic solvents through hydrolytic polycondensation followed by aging. By introducing the aging step, the viscosity of the as-prepared PSQ liquid is decreased by more than an order of magnitude, and the long-term viscosity stability is improved considerably. These variations are mainly attributed to the modification of the topology of the Si-O-Si network because the crosslinking density was influenced little by the aging. The viscosity of PSQ liquids obtained via aging at 80 °C was ∼4-5 × 10(3) mPa s at 30 °C and the viscosity increase was less than 25% after storage for 2 months at room temperature despite the many unreacted silanol (SiOH) groups present in the liquid.

A facile sol-gel-based method for the formation of monolithic polysilsesquioxane glasses from acid-catalyzed organotrimethoxysilane-water binary mixtures, free from alcohols and organic solvents, has been developed.

Cosolvent-free hydrolytic polycondensation of trimethoxy(3-sulfanylpropyl)silane under acidic conditions was found to yield thiol-containing polysilsesquioxane (PSQ) liquid. The resultant PSQ liquid is stable at room temperature and serves as a precursor of sulfur-containing transparent organic–inorganic hybrid monoliths prepared via ultraviolet (UV) photoinduced thiol–ene reaction. The factors that determine the UV transparency of the hybrids were investigated. Sulfur-containing organic–inorganic hybrids showing good transparency in the UV spectral region are obtained using a vinyl compound, which is transparent around the UV absorption edge of thiol groups.