Synthesis of lamellar mesoporous silica materials using LCs as templates

ABSTRACT

The study focuses on the synthesis of mesoporous silica materials using liquid crystals (LCs) formed in an aqueous mixture of cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS) as templates and tetrathoxysilane (TEOS) as precursor. For this purpose, the phase behavior and range of LC areas were determined at different temperatures, concentrations, and ratios of CTAB/SDS. It was found that LCs became denser with the increased of concentration of surfactants. The mesoporous materials were synthesized using LCs as templates at various temperatures, surfactant concentrations, and pH values. The mesoporous samples were characterized using SEM and nitrogen sorption analysis. The research results showed that the structure of synthesized samples were lamellar and their surface areas increased significantly with the increase of temperature in the temperature range of LCs, reaching about 900 m²/g at 60°C. The surfactant concentrations affect the thickness of pore wall and thereby the specific surface area of products. The specific surface area and the order of mesoporous sample increased gradually with the decrease of pH.

GRAPHICAL ABSTRACT

KEYWORDS:

• Cationic and anionic surfactants
• lamellar structure
• liquid crystal
• mesoporous materials