Abstract
The effect of drying on the phase transformation of mesoporous silica is investigated in detail. The as-synthesized hexagonal p6mm phase obtained under the experimental conditions employed is transformed to cubic Ia3d phase, even at room temperature, as the drying of the solid proceeds. Prolonging the synthesis period results in the formation of a well-ordered hexagonal mesophase, which is not further transformed into any other mesophases. The phase transformations observed here take place against the direction earlier proposed on the basis of packing parameters. The drying induced phase transformations are confirmed by using an in situ powder X-ray diffraction-differential scanning calorimetry instrument in which phase transformation is detected upon loss of water from the mesophase. By the redispersion of the SiO2-CTAB hybrid mesophase in water or ethyl alcohol synthesis of mesostructured films is also attempted.
