Superparamagnetic nanoparticles stabilized with free-radical polymerizable oleic acid-based coating

Nanoparticles of iron oxide play an important role on the field of nanotechnology and nanoscience presenting tremendous potential for various applications. Oleic acid has been shown to be a promising coating material, allowing to obtain monodisperse, uniform and stable nanoparticles. However, for certain applications which utilize the encapsulation of magnetic nanoparticles into polymer matrices it becomes necessary to use coating materials which exhibit functional groups in their structure capable of avoiding leaching problems. To this end, the present study aimed to develop magnetite nanoparticles coated with chemically modified oleic acid. The reactive functional group present in the fatty acid molecule can promote polymerization between the monomer species and the coating material with high encapsulation efficiency. The different steps of the reactions to obtain acrylated oleic acid were evaluated by Fourier transform infrared (FTIR) spectroscopy and H-1 nuclear magnetic resonance spectroscopy. The coated nanoparticles were characterized by FTIR, thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, Mossbauer spectroscopy, Raman spectroscopy and magnetization measurements. The coated nanoparticles showed high dispersibility with a uniform average size of 9.5 nm, saturation magnetization of 61.2 emu/g and superparamagnetic behavior, which make it a very promising for the formation of nanocomposites. (C) 2017 Elsevier B.V. All rights reserved.