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

Silica-titania (SiO2-TiO2) pomegranate-like (multicore-shell) microspheres were prepared by a three-step approach. Aqueous polymerization was used to graft SiO2 nanoparticles with the hydrophobic poly(methyl methacrylate) (PMMA) and the hydrophilic poly(oligo(ethylene glycol)methyl ether methacrylate) (POEOMA) to obtain SiO2-PMMA-POEOMA (SMOn). Tetrabutyl titanate was then hydrolyzed with the POEOMA segment to form SMOn-TiO2. The amorphous titania shell was then transformed into anatase nanoparticles after removing PMMA-POEOMA by calcination. The features of the hierarchically structured pomegranate-like SiO2-TiO2-Cn microspheres prepared by adding cetyltrimethyl ammonium bromide were changed. The maximum numbers of SiO2 sub-units decreased from 90, 1068, and 584 inside a SiO2-TiO2-1, SiO2-TiO2-2, and SiO2-TiO2-3 microsphere to 58,410, and 187 inside a SiO2-TiO2-C1, SiO2-TiO2-C2, and SiO2-TiO2-C3 microsphere, respectively. The SiO2-TiO2 hybrid materials also exhibited different photocatalytic activities for decomposing methyl orange. (C) 2015 Elsevier B.V. All rights reserved.