Synthesis and size control of uniform, spherically shaped hexagonal mesoporous silica

Spherical hexagonal mesoporous silica (HMS) was prepared at ambient temperature using dodecylamine (DDA) as the template and tetraethyl orthosilicate (TEOS) as the silica source. The properties of the HMS particles were characterised by X-ray powder diffraction, scanning electron microscopy and N ₂ sorption measurements, and the effects of DDA concentration, stirring speed and rate of TEOS addition were evaluated. The HMS samples exhibited substantial framework-confined and textural mesoporosity. The particle and pore sizes of the spherical HMS decreased with decreasing DDA concentration. With increasing stirring speed, the HMS particle size decreased slightly, and the size distribution narrowed. Increasing the rate of TEOS addition resulted in a decrease in HMS particle size. The findings indicate that DDA concentration, stirring speed and rate of TEOS addition are all important in controlling particle size and shape during HMS synthesis.