Synthesis of magnetite nanoparticle aqueous dispersions in an ionic liquid containing acrylic acid anion

Stable magnetite nanoparticle aqueous dispersions were prepared by precipitating ferrous ions in the presence of an ionic liquid containing acrylic acid anion, viz., N-methylimidazolium acrylic acid (MImAA) in air at high pH. The size of the as-prepared magnetite nanoparticles could be tuned from 12 nm to 20 nm depending on the concentration of MImAA in the medium. X-ray diffractions showed the presence of only Fe3O4 phase in the nanoparticles. The ionic liquid with some dimers was demonstrated to be an effective stabilizer for magnetite nanoparticle dispersions. The FTIR and TGA analysis confirmed the attachment of the acrylic acid anion in ionic liquid predominantly on the particle surface in the chelating bidentate configuration.