New strategy using glycol-modified silane to synthesize monodispersed mesoporous silica spheres applicable to...

A new approach focusing on the reactivity of a silica source was developed for the particle size control of monodispersed mesoporous silica spheres (MMSSs). A glycol-modified silanes, tetrakis(2-hydroxyethyl) orthosilicate was chosen as the silica source and successfully applied in the surfactant-templated synthesis of MMSSs in a very dilute alkaline alcohol-water mixture. Due to its higher hydrolysis rate compared with tetraalkyl orthosilicates, it took less time for the primary particles to come out, resulting in the formation of small particles with diameters falling in the low submicrometer range. The resultant spheres possessed a well-ordered mesoporous structure, which was typically MCM-41-type hexagonal. The MCM-48-type cubic spheres could also be obtained by changing the reaction condition. The monodispersity and particle size of the spheres were precisely controlled by the adjustment of the solvent composition in the methanol-ethanol-water system. Furthermore, ionic colloidal crystals exhibiting a well-defined stop band in the visible light region could be fabricated from the resultant MMSSs for the first time. This work encourages the further utilization of MMSSs in photonics as well as in catalysis or biochemistry.