| Oriented mesoporous; silica films have been synthesized at air-water and solid-water interfaces by a surfactant-based supramolecular templating technique under quiescent aqueous acidic conditions. Solid substrates include freshly cleaved Muscovite mica, pyrolytic graphite, and sputter-deposited gold. Convergent evidence from PXRD, SEM, TEM, AFM, POM and gas adsorption isotherms have shown that the silica films are mesoporous; and in closely packed hexagonal phase. Registry of silicate-surfactant assemblies on atomically flat substrates, mica and graphite, has been established by AFM, SEM and POM studies. Control of film properties such as the degree of polymerization of silica, film thickness, and hexagonal packing order has been demonstrated by adjusting acidity, temperature, and post-treatment conditions.; Mesoporous silica has also been synthesized with a range of spectacular curved shapes. Optical birefringence has been observed for some of the shapes and the origin has been traced to the hexagonally close packed arrangement of silica channels. The mesostructure-morphology relationship of gyroid, discoid and fiber shapes have been established by TEM, SEM, AFM and POM studies. The channel structure of mesoporous silica films and some curved shapes are thought to be initiated by defects in the growth liquid crystalline seed. A distinct mode of formation has been found for micron size mesoporous silica spheres. Low acidity and high temperatures favor sphere formation and the growth process is based on colloidal flocculation. The main factors that contribute to the nucleation, growth and form of mesoporous silica morphologies have been identified.; Proof-of-concept for building hierarchical mesoporous structures has been illustrated through the use of patterned self-assembled monolayers (SAM) on gold. Mesoporous silica is found to preferentially grow on SAM patterned regions of the film. |
