Abstract
A layer-by-layer method is used to coat titania on spherical polystyrene (PS) powders in an aqueous solution. To increase surface charge density, a negatively charged PS powder is sequentially adsorbed by a cationic polyethylenimine (PEI)/anionic ammonium salt of poly(acrylic acid)/cationic PEI polyelectrolytes. A precursor of a negatively charged titanium bis-ammonium lactate dihydroxide (TALH) is then precipitated onto the above positively charged PS. Repeating the coating processes of TALH/PEI in an aqueous solution, a uniform, multilayer TALH/PEI coating on PS powder is formed. A crystalline, spherical, hollow titania powder is then obtained by hydrothermal treatment of the above powder in an aqueous solution at temperatures higher than 350°C. © 2008 The American Ceramic Society.