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 distillation–precipitation 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 TiO₂ (a-TiO₂) is incorporated into the shell of a microsphere by a sol–gel method. The a-TiO₂-incorporated pH-responsive pMET composite [pMET/TiO₂] hollow microspheres were tested as a photocatalyst in acidic and neutral conditions. The photocatalytic performance of the hollow pMET/TiO₂ 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).