Formation at low surfactant concentrations and characterization of mesoporous MCM-41

At low concentrations of cetyltrimethylammonium bromide, all silica-based mesoporous materials with hexagonal phase have been synthesized via interactions between self-assembled surfactant molecule aggregates and anionic silicate polymers. The resulting materials are characterized by XRD, FT-IR, solid state ²⁹Si MAS NMR, thermal analysis and N₂ adsorption-desorption measurements. After soluble ions are removed, the interacted between surfactant micelles and silicate polymers are reorganized and then form mesostructures. The hexagonal framework is consistent with amorphous silica gel. The structures of materials depend on the synthesis conditions. Hydrothermal process improves the interactions between molecules and increases the degree of framework silicon atom polymerization. The surface area and the mesopore volume of the material prepared at 100°C increase by 87% and 71%, respectively, compared with those obtained at room temperature.