Preparation and Characterization of Solvent-free Fe3O4 Nanofluids

The surfactant was used to functionalize the nanoparticles to prepare solvent-free nanofluids. To prevent Fe3O4 nanoparticles from agglomerating and improve the dispersion of Fe3O4 nanoparticles, the solvent-free Fe3O4 nanofluids were synthesized through surface modification. Magnetic Fe3O4 nanoparticles were firstly prepared by chemical co-precipitation method. Then graft the quaternary ammonium salt (CH3O)(3)Si(CH2)(3)N+(CH3)(2)(C18H37)Cl-, which has silanol groups, on Fe3O4 nanoparticles with hydroxyl groups. Finally, the chloridion was replaced with the anion C9H19-C6H4 (OCH2CH2)(20)O(CH2)(3)SO3 through an ion-exchang process. An organic layer was formed on the surface of Fe3O4 nanoparticles, and made the Fe3O4 nanoparticles from black powder to brown fluid ( at room temperature). The solvent-free Fe3O4 nanofluids were characterized by X-ray diffraction, Fourier transform infrared spectrum, differential scanning calorimetry, thermogravimetric analysis, transmission electron microscopy and rheometer. The Fe3O4 nanoparticles were monodispersed in solvent-free nanofluids, and the content of Fe3O4 nanoparticles in the nanofluids proved to be about 12%. The loss shear modulus G '' was higher than the storage shear modulus G'.