Synthesis of Mesoporous Silica Nanoparticles via Controlled Hydrolysis and Condensation of Silicon Alkoxide

The cooperative self-assembly of silica species and cationic surfactant cetyltrimethylammonium chloride (CTA+Cl− or CTAC) and the formation of mesoporous silica nanoparticles occur following the hydrolysis and condensation of silica precursor TEOS in the solution. The particle size can be controlled from ∼25 nm to ∼200 nm by adding suitable additive agents (e.g., inorganic bases, alcohols) which affect the hydrolysis and condensation of silica species. The in situ pH measurement of synthesis system is introduced to investigate the formation process of mesoporous silica nanoparticles. Our results show that a certain acid−base buffer capacity of the reaction mixture in a range of pH 6−10 is essential for the formation of mesoporous silica nanoparticles in the TEOS−CTA+ system. The nucleation and growth process of the nanoparticles can be extended into the self-assembly system of inorganic−surfactant and the formation of mesophase in aqueous media.