Synthesis of titania hollow microspheres using non-aqueous emulsions

Hollow titania microspheres ranging from 100 nm to a few micrometres in diameter were synthesized by a novel method using surfactant-stabilized non-aqueous emulsion droplets. Well-defined micron-sized hollow spheres with amorphous titania walls typically 50 nm thick were prepared by addition of water to formamide dispersions of hexadecane droplets containing titanium ethoxide. In contrast, addition of titanium ethoxide to formamide–water droplets dispersed in hexadecane produced hollow spheres of amorphous titania only 100 nm in diameter. In both cases, hydrolysis/condensation reactions at the formamide/oil interface gave rise to intact shells that could have uses as low density pigments, dyes, self-repairing coatings, photoactive storage/release agents, as well as compartmentalized structures in nanotechnology.