Iron compounds as coatings on polystyrene latex and as hollow spheres

Sub-micrometer-sized anionic polystyrene latices have been coated with unif orm layers of iron compounds by aging, at elevated temperature, dispersions of the polymer colloid in the presence of aqueous solutions of ferric chlo ride, urea, hydrochloric acid, and polyvinylpyrrolidone. The thickness of t he deposited layers could be altered by suitable adjustment of the reactant concentrations, and they could also be increased by further aging of the c oated particles in the presence of aqueous solutions of ferric chloride. Ho llow colloidal spheres of iron compounds were obtained by calcination of th e so-coated polystyrene latices at elevated temperature in air. Different c hemical compositions of hollow colloidal spheres were obtained by heating t hem in hydrogen, (C) 2000 Academic Press.