Silica based nanoparticles gelation

Wang Zakeeruddin SM. Comte Exnarl. Gratzel M. Gelation of Ionic Liquid-based Electrolytes with Silica Nanoparticles for Quasi-solid-state Dye-sensitized Solar Cells, J. American Chemical society 2003,125, 1166-1167. 

In our laboratory, we have recently conducted gelation studies of silica nanopardcles in microgravity during the STS-95 space shuttle mission (28). Stable silica nanoparticle dispersions may be form either by polymerization of silicic acids in an aqueous system or through hydrolysis and condensation of silicon alkoxides (the sol-gel or Stober route). Comparison of small-angle x-ray scattering (SAXS) measurements of Ludox, a commercial aqueous silicate with acid- and base-catalyzed alkoxides shows that only aqueous silicate sols are uniform, whereas alkoxides generate fractal particles. As Brinker and Scherer point out (29), these results illustrate that sols derived from aqueous silicates are... 

Wang, P., Zakeeruddin, S.M., Comte, P., Exnar, I., and Graetzel, M. (2003) Gelation of ionic liquid-based electrolytes with silica nanoparticles for quasi-solid-state dye-sensitized solar cells. /. Am. Chem. Soc., 125, 1166-1167. 

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