Formation of mesoporous silica thin films on oxide substrates by casting

The preparation of mesoporous silica thin films with bi-dimensional hexagonal pores whose channel axis oriented parallel to the plane of the film on oxide substrates has been studied using casting, X-ray diffraction (XRD), scanning electron spectroscopy (SEM), N-2 adsorption-desorption and thermogravimetry (TG). XRD and SEM observations show that the surfactant-silica mesostructured thin films are synthesized on the substrates using a cetyltrimethylammonium bromide (CTMABr)-tetraethyl orthosilicate (TEOS) gel under acidic conditions at ambient temperature. XRD and N-2 adsorption-desorption studies reveal that the powdered mesoporous silica composite remains structurally stable and ordered after template removal and that the supported thin films are plausibly stable after template removal but less stable and ordered than the powdered composite. TG analysis indicates that the template supercritical fluid extraction (SFE) efficiency reaches 87%. The influences of the surfactant-substrate and film-substrate interactions on the formation and structural stability of the thin films are discussed. (c) 2005 Elsevier Inc. All rights reserved.