Characterization of the structure of mesoporous thin films grown at the air/water interface using X-ray surface techniques

Grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity have been used in situ to study the structure of surfactant-templated silica films grown at the air/water interface at different depths in the film. The results confirm that cylindrical silica-encased surfactant micelles are predominantly organized into a two-dimensional hexagonal structure, with the long axis parallel to the surface of the film. The arrangement of the micelles is well orientated near to the air/film interface but becomes disordered deeper into the sample. GIXD also reveals the existence of vertical channels extending down from the bottom of the film. This suggests a transition from in-plane to unconstrained growth.