A facile template-free synthesis of pH-responsive polyelectrolyte/amorphous TiO₂ composite hollow microcapsules for photocatalysis

Abstract

This paper presents a novel, facile method for fabricating pH-responsive inorganic/organic composite microspheres with hollow structures in the absence of a step for the removal of the core. Using polyelectrolyte (hydrogel) hollow microspheres without a need for further calcination and chemical etching, minimally cross-linked poly(methacrylic acid/ethylene glycol dimethacrylate/3-(trimethoxysilyl) propylmethacrylate), poly(MAA/EGDMA/TMSPM) [pMET] microspheres were prepared by a distillationprecipitation method. Once the pMET microspheres disperse in 2-propanol, the hollow structure is clearly observed and can be maintained more rigidly in a dry state after amorphous TiO 2 (a-TiO 2 ) is incorporated into the shell of a microsphere by a sol-gel method. The a-TiO 2 -incorporated pHresponsive pMET composite [pMET/TiO 2 ] hollow microspheres were tested as a photocatalyst in acidic and neutral conditions. The photocatalytic performance of the hollow pMET/TiO 2 composite microcapsules under neutral condition was better than that under acidic conditions due to their large active surface and strong adsorption ability against methylene blue (MB). † Electronic supplementary information (ESI) available: SEM images of poly(MAA/EGDMA) microspheres; OM images of poly(MAA/EGDMA) microspheres dispersed in 2-propanol and water; XRD pattern of pMET/a-TiO 2 composite microcapsules; additional schematic illustration; thermodegradation and photodegradation of MB without photocatalysts; FT-IR spectra of all samples. See Scheme 1 Schematic illustration for the synthetic process of poly-(MAA/EGDMA/TMSPM)/a-TiO 2 composite microcapsules: CLSM image of the poly(MAA/EGDMA/TMSPM) microspheres dispersed (a) in aqueous solution and (b) 2-propanol, and (c) EDX-maps of (green) titanium and (red) carbon from the hollow poly(MAA/EGDMA/ TMSPM)/a-TiO 2 composite microcapsules. 59258 | RSC Adv., 2015, 5, 59257-59262 This journal is

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“…In our previous work, we reported that MB molecules in an aqueous solution were decomposed by the high temperature from a strong UV light. 30 Thus, a weak UV light (16 W) was used to measure the precise photodegradation performance of the photocatalysts. All photocatalyst powders were prepared in the dark with magnetic stirring for 1 h before UV light irradiation.…”