Synthesis and characterization of SiO2–PMMA–POEOMA structures and SiO2–TiO2 pomegranate-like hybrid microspheres for the photodecomposition of methyl orange

Abstract Silica–titania (SiO 2 –TiO 2 ) pomegranate-like (multicore–shell) microspheres were prepared by a three-step approach. Aqueous polymerization was used to graft SiO 2 nanoparticles with the hydrophobic poly(methyl methacrylate) (PMMA) and the hydrophilic poly(oligo(ethylene glycol)methyl ether methacrylate) (POEOMA) to obtain SiO 2 –PMMA–POEOMA (SMOn). Tetrabutyl titanate was then hydrolyzed with the POEOMA segment to form SMOn–TiO 2 . The amorphous titania shell was then transformed into anatase nanoparticles after removing PMMA–POEOMA by calcination. The features of the hierarchically structured pomegranate-like SiO 2 –TiO 2 –Cn microspheres prepared by adding cetyltrimethyl ammonium bromide were changed. The maximum numbers of SiO 2 sub-units decreased from 90, 1068, and 584 inside a SiO 2 –TiO 2 -1, SiO 2 –TiO 2 -2, and SiO 2 –TiO 2 -3 microsphere to 58, 410, and 187 inside a SiO 2 –TiO 2 -C1, SiO 2 –TiO 2 -C2, and SiO 2 –TiO 2 -C3 microsphere, respectively. The SiO 2 –TiO 2 hybrid materials also exhibited different photocatalytic activities for decomposing methyl orange.