Simple route to prepare different core–shell structured silica-based microspheres

摘要

Different core–shell structured silica–titania (SiO–TiO) nanocomposites were successfully synthesised in two successive stages. In the first stage, the core was synthesised by preparing poly[oligo(ethylene glycol)monomethyl ether methacrylate] (POEOMA) on the modified surface of silica nanoparticles (SiO–POEOMA). In the second stage, the shell was formed by depositing or coating tetrabutyl titanate (TBT) with SiO-polymer to obtain cauliflower-like, cauliflower–pomegranate-like and pomegranate-like SiO–POEOMA–TiO microspheres; the weight ratio of added SiO–POEOMA to TBT (1:0.146, 0.293 and 0.439) was then adjusted. Later, the polymer layer was removed to obtain the cauliflower-like, cauliflower–pomegranate-like and pomegranate-like core–shell structured SiO–TiO microspheres (CMs, CPMs and PMs). X-ray diffraction results showed that the TiO shell was a pure anatase phase. SiO–TiO microspheres were also characterised by N adsorption–desorption; the results showed that a pore structure was found in the porous shell. Extensive porosity was generated in the shell because POEOMA was used as a template and pore-forming agent; the structure of CMs, CPMs and PMs remained almost unchanged. These results also showed that pore volumes and specific surface areas of the final products derived from N sorption decreased as the content of TBT increased. PMs with the highest content of TiO showed the most efficient photocatalytic activity.