| In this paper, preparation of water-based magnetic fluid by using nanometer Fe3O4, synthesized by different methods, as basic substance was systematically studied.1. Fe3O4 magnetic nanoparticles were prepared by the co-precipitation of Fe3+ and Fe2+, NH3·H2O was used as the precipitating agent to adjust the pH value, and the aging of Fe3O4 magnetic nanoparticles was accelerated by microwave (MW) irradiation. The Ms value of Fe3O4, aged under microwave, was higher than those aged for 7 days at room temperature, which was due to the improved crystalline structure of nanoparticles by MW. Thereafter, the surface of Fe3O4 magnetic nanoparticles was modified by stearic acid. The results indicated that a covalent bond was formed by chemical reaction between the hydroxyl groups on the surface of Fe3O4 nanoparticles and carboxyl groups of stearic acid, which changed the polarity of Fe3O4 nanoparticles. The dispersion of Fe3O4 in organic solvent was greatly improved after modification. Effects of reaction time, reaction temperature and concentration of stearic acid on particle surface modification were investigated. In addition, Fe3O4/polystyrene (PS) nanocomposite was synthesized by adding surface modified Fe3O4 magnetic nanoparticles into styrene monomer, followed by the radical polymerization. Results revealed that the thermal stability of PS was not significantly changed after adding Fe3O4 nanoparticles. The Fe3O4 magnetic fluid had excellent stability, and had susceptibility of 4.46×10-8 and saturated magnetization of 6.56 emu/g. In addition, the mean size d (0.99)num of magnetic Fe3O4 nanoparticles in the fluid was 36.19 nm.2. Fe3O4 magnetic nanoparticles were prepared by the co-precipitation of Fe3+ and Fe2+ with surfactant. Thereafter, to enhance the compatibility between the magnetic Fe3O4 nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticles surface. The effects of... |
