- Synthesis of supported and free-standing thin mesoporous silica films from solution was investigated. It has been reported that the initial reactant concentration as well as the nature of the substrate affect the structure and symmetry of the resulting films. We found that by preparing the films on a polymer-coated substrate, one could de-couple the two parameters and control the structure of the resulting film exclusively via the concentration of reactants in solution. In addition, dissolution of the polymer layer in an organic solvent resulted in free- standing films, of hexagonal (MCM 41) or lamellar mesoporous phases, that could be transferred onto a target substrate. Small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements were employed to characterize the films.