A new ‘pH-induced rapid colloid aggregation’ method to prepare micrometer-sized spheres of mesostructured silica in water-in-oil emulsion

Micrometer-sized silica spheres with mesoporous structures were prepared by a new pH-induced rapid colloid aggregation method in water-in-oil (W/O) emulsion with PEG (poly(ethylene glycol)) or the mixtures of PEG and sodium dodecylsulphate (SDS) as templates. The effect of the reactant composition and the operation conditions on the particle morphology was investigated by scanning electron microscopy (SEM) observation, including the molecular weight of PEG, the amount of the reactants, stirring speed, and the continuous phase characteristic of the emulsion. The prepared mesoporous silica spheres, characterized by nitrogen adsorption and desorption and transmission electron microscopy (TEM), exhibited high surface areas (∼700–980 m2/g) and large pore volumes (∼0.68–1.48 mL/g). And the spheres exhibiting narrow pore size distributions were obtained by optimizing the composition of the reactants. Finally, the mechanism of this synthetic route was discussed.