Synthesis of Nanosized Multilayered Silica Vesicles with High Hydrothermal Stability

Nanosized multilayered silica vesicles have been synthesized through a dual-template way by using cetyltrimethylammonium bromide (CTAB) and C3F7O(CFCF3CF2O)(2)CFCF3 CONH(CH2)(3)N+(C2H5)(2)CH3I-(FC-4) as the cotemplates and tetraethyl orthosilicate (TEOS) as the siliceous precursor. According to transmission electron microscopy, X-ray diffraction, and N-2 sorption analysis, the formation of the multilayered silica vesicles passed through the route of the normal mesoporous silica spheres (MCM-41) to irregular hexagonal structures with cavities inside MCM-41 spheres and finally to the small-sized multilayered siliceous vesicles with the increase of FC-4/CTAB molar ratio. The possible mechanism of the two kinds of micelles cooperation was discussed. The synthesized silica vesicle spheres were 30-40 nm with a few shells that may facilitate the transport of the molecules. Furthermore, the vesicular structure was also obtained by aging at 150 degrees C, which maintained high surface area even after hydrothermal treatment in boiling water for 48 h. The higher hydrothermal stability, high surface area, and pore volume would benefit the loading of catalysts and increase the adsorption capacity.