Inorganic salt aided synthesis of monolithic silica with meso/macro hierarchical structure

The inorganic salts, such as NaCl, NaNO3 or Na2SO4, were demonstrated to have great influence on the mesostructure formation of the silica monolith with well-defined macro–mesoporous hierarchical structure synthesized in weak acidic medium (acetic acid aqueous solution) using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (P123) as the surfactant. The results of XRD and TEM showed that the ability of the inorganic salts for promoting formation of ordered mesostructure followed the sequence of NaCl > NaNO3 > Na2SO4. In addition to the mesopore, the existence of well-defined macropore was characterized by SEM and mercury porosimetry. Moreover, it was interesting to mention that the cross-linking degree of the silica monolith was greatly enhanced with the addition of inorganic salts. The formation of carbon monolith with well-defined macropore and mesopore was illustrated by replica of the hierarchical silica monolith.