A versatile route to silsesquioxane nanoparticles from organically modified silane precursors

Hybrid organo-silica nanoparticles (silsesquioxanes) with particle diameters in the range 3.5 to ≈300 nm have been prepared by hydrolysis and condensation of organotrimethoxysilane precursors in the presence of water, surfactant and sodium hydroxide at room temperature. The hybrids were obtained reproducibly using various amounts of two different emulsifiers and constant concentrations of sodium hydroxide and the precursors. In addition to fairly monodisperse nanoparticles, rings and chains were also obtained depending on the surfactant concentration and type of surfactant used. The formation of complex superstructures seems to be at least partly related to the water solubility of the surfactant. The retention of the covalently bonded organic groups was confirmed by solid-state 13C and 29Si MAS NMR and FTIR spectroscopies. The method described here complements previously described routes to silsesquioxane nanoparticles in terms of particle size achievable.