Abstract
Silica sols have been prepared in an alcoholic solution by hydrolysis and condensation of TEOS (tetraethyl-ortho-silicate) molecules as a function of water and nitric acid concentration. The polymers are intended as precursors for ceramic, gas separation membranes. These molecules show fractal behavior as determined by SAXS (Small Angle X-ray Scattering). Microporosity of dried and calcined silica polymers is determined by N2-adsorption at 77 K. Fractal dimension and porosity increase with increasing acid concentration. Both the sol structure and the drying kinetics determine the porosity values. N2-adsorption isotherms are not very suitable for the determination of pore size distributions of microporous silica.
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Nair, B.N., Elferink, J.W., Keizer, K. et al. Preparation and structure of microporous silica membranes. J Sol-Gel Sci Technol 8, 471–475 (1997). https://doi.org/10.1007/BF02436884
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DOI: https://doi.org/10.1007/BF02436884