In-Situ SAXS Studies on the Formation of Silicate/Surfactant Mesophases with Solubilized Benzene under Acidic Conditions

The formation of mesoscopically ordered silica/surfactant composites under acidic synthesis conditions is studied by time-resolved in-situ small-angle X-ray scattering (SAXS) using synchrotron radiation. Benzene is used a an additive which acts as a weak swelling agent although most of the benzene molecules are found to reside near the surfactant/silicate interface region rather than in the micelle cores. With increasing relative amounts of benzene, the curvature of the micellar aggregates decreases, which finally leads to a transition from (hexagonally) rodlike to lamellar; a mechanism for this change in curvature is suggested.