Distinctive Features of the Formation of Spherical Mesoporous Silica Particles below Room Temperature

We have developed a technique for controlling internal structure parameters (specific surface area, pore volume, and pore size) of spherical amorphous silica particles by varying the synthesis temperature. The particles have been prepared through hydrolysis of tetraethyl orthosilicate in an ethanol–water–ammonia mixture in the presence of cetyltrimethylammonium bromide at temperatures from –20 to 50°C. We have studied the morphology and adsorption structure properties of the synthesized materials and demonstrated the effect of reaction mixture temperature on the particle formation mechanism. The synthesized particles, 500–1100 nm in diameter, contain pores 3 to 50 nm in size up to 0.8 cm³/g in volume, with a specific surface area of up to 1000 m²/g. The particles prepared below room temperature have a core/shell structure.