Surface modification of carbonyl iron with organosilicon block copolymer performed by wet ball milling

Abstract

The paper shows the possibility of producing plate-like carbonyl iron particles covered with a surface layer modified with a poly(dimethylsiloxane) – poly(phenylsilsesquioxane) block copolymer by means of wet ball milling. At the initial stages, the milling is accompanied with the formation of an intermediate layer enriched with rigid poly(phenylsilsesquioxane) blocks followed by the copolymer precipitation. Long-term milling leads to the complete decomposition of the polymer on the surface with the formation of silicon oxycarbide and silicon carbide, with the shape of the particles being changed from plate-like to stone-like. Mechanochemical treatment goes also with dehydrogenation/hydrogenation of the milling medium followed by the formation of alkyl derivatives in the liquid and carbides in the particles as well as oxidation of the medium with the formation of ester groups. Other additives of various types (sodium dodecyl sulfate, stearic acid, N-phenylanthranilic acid) introduced into the block copolymer solution under milling facilitates the formation of multicomponent modifying layers. The most of modifying organic layers formed under wet ball milling have been shown to exhibit anticorrosive properties. The particles covered with as-modified layers may be used as magnetic fillers for microwave materials.