Synthesis of hollow mesoporous silica microspheres through surface sol–gel process on polystyrene-co-poly(4-vinylpyridine) core–shell microspheres

Synthesis of hollow mesoporous silica microspheres (HMSM) through directed surface sol–gel process of tetraethylorthosilicate (TEOS) on the template of core–shell microspheres of polystyrene-co-poly(4-vinylpyridine) (PS-co-P4VP) in the presence of the CTAB surfactant in neutral aqueous solution at room temperature is discussed. Ascribed to the inherently pendent catalyst of the Lewis alkaline P4VP segment on the template surface of the PS-co-P4VP core–shell microspheres, the sol–gel process of TEOS is directed exclusively onto the template, and thus well-defined HMSM are fabricated. The thickness of the mesoporous silica shell of HMSM can be tuned by changing the weight ratio of the template of the PS-co-P4VP core–shell microspheres to the coating material of TEOS. Following this method of directed surface sol–gel process, well-defined HMSM with shell thickness ranging from 13 to 39 nm are synthesized. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD) and nitrogen adsorption–desorption analysis are applied to characterize the synthesized HMSM.