Facile preparation of silica hollow microspheres by precipitation-phase separation method

Silica hollow microspheres with an eccentric interior and varied porous shell structures, including mesoporous, macroporous and monoporous shells, were prepared by a simple and efficient precipitation-phase separation method. We found that the morphology, size and porous shell structures of the silica hollow microspheres depended strongly on process parameters such as the amount of ammonia, the ratio of TEOS/polystyrene and the organic solvent. The prepared silica hollow microspheres were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption measurements and thermogravimetric analysis. Based on our results, we propose a possible formation mechanism of the hollow and eccentric structure.