Journal of Porous Materials 6, 19–24 (1999) c  1999 Kluwer Academic Publishers. Manufactured in The Netherlands. Preparation of Mesostructured Materials from Tetramethoxysilane and Alkyltrimethylammonium Salts and Their Conversion to Porous Silica MAKOTO OGAWA PRESTO, Japan Science and Technology Corporation, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan; and Institute of Earth Science, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan NAOKI YAMAMOTO Institute of Earth Science, Waseda University, Nishiwaseda 1-6-1, Shinjuku-ku, Tokyo 169-8050, Japan Abstract. A novel synthetic route for the preparation of the porous silica by a supramolecular templating mechanism is reported. By depositing the precursor solution containing tetramethoxysilane and hexadecyltrime- thylammonium chloride on glass plates at an elevated temperature (60 ◦ C), mesostructured silica-hexadecyltrime- thylammonium chloride composites with the size of a few mm to a cm have been prepared. The composition of the resulting products can be controlled by simply changing the composition of the starting mixtures. By the calcination of the as synthesized mesostructured materials, porous silica with large surface area was obtained. Due to the ease of operation, the present method is a simple way to prepare porous silica alternative to the procedures reported for the preparation of mesoporous silicas (MCM-41 and FSM-16). Keywords: porous silica, mesostructured materials, supramolecular template, surfactant 1. Introduction The preparation of porous inorganic solids with con- trolled pore structures and surface properties has ex- tensively been investigated from both scientific and practical viewpoints. Since the discovery of mesopo- rous silicas by supramolecular templating mechanisms [1–5], the preparation of mesostructured inorganic- surfactant composite materials has attracted increas- ing interest in the fabrication of inorganic/surfactant biphase arrays [1–9]. Although these solids may have potential applicability as adsorbents [10, 11], catalysts [12–14], and hosts for inclusion compounds [15–18], the mechanism for the formation and the detailed struc- ture of the resulting composites are still controver- sial. The transformation of a layered silicate, kanemite, during the intercalation of cationic surfactants [1–3] and the cooperative assembly of soluble silicate and surfactants [4–9] have been proposed to be two typical reactions for the formation of the mesostructured silica- surfactant composites. Many efforts are being made in order to elucidate the reaction mechanisms and the structures of the products further [19–29]. On the other hand, modified sol-gel processes have been successfully applied to prepare monoliths and thin films of the silica-surfactant mesostructured materials [30–39]. In the reactions developed for the prepara- tion of thin films of the silica-surfactant mesostructured materials [30–34], the mesostructures were thought to form during the evaporation of solvents. This is a distinct difference from the reactions reported for the preparation of other mesoporous silicas (M41S and FSM) in which the silica-surfactant composites have been obtained as precipitates of very fine particles. The present method can be regarded as a novel and simple way for the preparation of mesoporous silicas, since the reaction proceed at room temperature and the composition can be controlled by simply changing