Development and vapor sorption assessment of dimorphic SiO2 porous substrates

Dimorphic SiO2 pore substrates (i.e. mesoporous solids made of separated grains of cylindrical and spherical void entities) are synthesized from several possible silicon alkoxide sol–gel routes in the presence of triblock copolymer surfactants that act as pore templates. The preparation method consists in bringing together colloidal systems in which pore-templating (spherical and cylindrical) supramolecular arrangements are dispersed within a gellifying silica matrix arising from the reaction between tetraethoxysilane and micellar aqueous dispersions of triblock copolymer surfactants. The goal is to end with a colloidal gel structure in which two kinds of micellar pore templates are repartitioned throughout the silica gel matrix. Thermal treatment of this gellifying arrangement brings about a granular porous solid of a dimorphic nature. Nevertheless, monomorphic pore arrangements can still be obtained depending on the types of surfactants and preparation conditions. Characterization of these SiO2 adsorbents in terms of their pore structure properties is carried out by N2 sorption, electron microscopy and X-ray diffraction.

Overall view of the N2 sorption isotherms at 76 K on SiO2 dimorphic and monomorphic substrates arising from the mixing of sol–gel dispersions of P123, F127, and CTAB surfactants.Figure optionsDownload as PowerPoint slide