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A novel and effective method for synthesis of mesoporous silica is reported in this paper. The method was based on the use of the tetraethoxysilane (TEOS) as precursor and the layered liquid crystals (LCs) as templates formed by cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The range of the LCs was determined by exploring the phase behavior of the system with different ratios and concentrations of CTAB and SDS. The effects of the ratio of CTAB/SDS and the ratio of H2O and TEOS (defined as R) on the properties of mesoporous materials were studied. The results indicated that the specific surface area of mesoporous silica increased initially and then decreased with the increase of both R value and CTAB in the positive region. SEM photos showed that the synthesized mesoporous silica had a distinct lamellar structure.

Liquid crystals formed in aqueous mixtures of cationic and anionic surfactants were used as structure- directing templates for preparation of mesoporous silicas. For this purpose, micellar particle sizes and liquid crystal regions in the mixed system containing cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were investigated by Melvin laser particle size analyzer and polarizers, respectively. The formation of large organized assemblies was closely related to both the total surfactant concentrations and mixing ratios. Micelles formed at low total concentration while liquid crystals formed at high total concentration. The mixtures of CTAB and SDS favored the formations of large organized assemblies when the molar fraction of CTAB was 0.30 or 0.70. Using tetraethoxysilane as precursor and liquid crystals as templates, mesoporous silicas were prepared at different total concentrations of surfactants when molar fraction of CTAB was fixed at 0.70. Transmission electron microscopy results revealed that ordered mesoporous silicas with lamellar pore channels were prepared. Nitrogen adsorption-desorption determinations showed that these materials exhibited a pore size about 4.5 nm. In addition, the surface areas increased significantly with the increase of total surfactant concentrations. This work provided a simple and effective approach to synthesize lamellar mesoporous silicas.