Synthesis of silica mesoporous crystals with controlled structure and morphology using gemini surfactant

Silica mesoporous crystals with different morphologies were prepared based on the self-assembly of the gemini cationic surfactant [C16H33N+(CH3)2(CH2)3N+(CH3)3]Br2(C16-3-1) and tetraethyl orthosilicate (TEOS) in water under acidic condition. By controlling the kind of acids (H2SO4 or HCl), temperature and synthesis compositions, three well-ordered silica mesoporous crystals, cubic Fm3¯m, three-dimensional hexagonal P63/mmc   and cubic Pm3¯n, with distinct morphologies were synthesized. In the synthesis system with H2SO4, the crystals changed the structure from Pm3¯n to Fm3¯m with decrease in acidity and increase in synthesis temperature; and in the synthesis with HCl, the crystals with Fm3¯m and P63/mmc were synthesized by changing the synthesis compositions, especially C16-3-1/H2O and C16-3-1/TEOS molar ratios.