Abstract
Nanoporous ceramic materials, including mesoporous silica (NIPS), fabricated using supramolecular assemblies of surfactant molecules as templates have attracted much attention. In order to obtain nanopores, such organic templates are generally removed from mesostructured organic/inorganic composites by calcination, where the composites are treated in air at a temperature higher than 300°C. However, this conventional process is not suitable, particularly for thin films, since it leads to film shrinkage and generates a considerable amount of internal stress, resulting in distortion or even breakage of the film. We report here a novel approach, which we have named "photocalcination", that achieves the elimination of surfactant molecules from the silica/surfactant composite films while preserving their periodic nanostructures. This method is based on the photochemical decomposition of organic molecules under irradiation with a vacuum ultraviolet light of 172 nm wavelength. Since our process can be conducted at low temperature of about 40°C, nanostructure distortion is much less than that caused by conventional calcination.
