Preparation and modification of ZnO microspheres using a Pickering emulsion as template

ZnO microspheres were prepared and modified by a novel Pickering emulsion route for the first time. The water dispersions of ZnO nanoparticles were emulsified with 1-hexanol to prepare O/W Pickering emulsion, in which ZnO nanoparticles spontaneously assembled at the surface of the droplets and the core-shell structures of 1-hexanol/ZnO were formed; after the subsequent centrifugation, wash, and desiccation process, ZnO microspheres were obtained. The influence of the emulsification temperature on the structure and average diameter of ZnO microspheres was investigated; the surface of ZnO microspheres was modified by the homogeneous precipitation reaction of methyl oxalate with zinc nitrate. The ZnO microspheres prepared at 20 degreesC had hollow structures; with the rise of emulsification temperature, the average diameter of ZnO microspheres decreased and their hollow features became indistinct. (C) 2004 Elsevier B.V. All rights reserved.