Size-controlled preparation of magnetite nanoparticles in the presence of graft copolymers

Stable aqueous iron oxide nanoparticle dispersions were prepared by coprecipitation of ferrous (Fe2+) and ferric (Fe3+) aqueous solution by a base in the presence of graft copolymers, poly(glycerol monoacrylate)-g-poly(PEG methyl ether acrylate) (PGA-g-PEG). PGA-g-PEG was prepared by acidic hydrolysis of poly(solktal acrylate)-g-poly(PEG methyl ether acrylate), which was synthesized by copolymerization of solktal acrylate and PEG methyl ether acrylate by atom transfer radical polymerization (ATRP). The size of the magnetite nanoparticles can be controlled from 4 nm to 18 nm by varying the graft density of the graft copolymers. Structural characterization using X-ray diffraction showed the presence of only the magnetite phase in the nanoparticles. Thermogravimetric analysis confirmed the presence of the graft copolymers on the magnetite surface. The magnetic characterization of the nanoparticles showed that they were superparamagnetic at room temperature.