Synthesis and Research of Water-based Magnetic Fluid

Abstract: In this paper, preparation of water-based magnetic fluid by using nanometer Fe_3O_4, synthesized by different methods, as basic substance was systematically studied.1. Fe_3O_4 magnetic nanoparticles were prepared by the co-precipitation of Fe~(3+) and Fe~(2+), NH_3·H_2O was used as the precipitating agent to adjust the pH value, and the aging of Fe_3O_4 magnetic nanoparticles was accelerated by microwave (MW) irradiation. The Ms value of Fe_3O_4, 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 Fe_3O_4 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 Fe3O_4 nanoparticles and carboxyl groups of stearic acid, which changed the polarity of Fe3O_4 nanoparticles. The dispersion of Fe_3O_4 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, Fe_3O_4/polystyrene (PS) nanocomposite was synthesized by adding surface modified Fe_3O_4 magnetic nanoparticles into styrene monomer, followed by the radical polymerization. Results revealed that the thermal stability of PS was not significantly changed after adding Fe_3O_4 nanoparticles. The Fe_3O_4 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 Fe_3O_4 nanoparticles in the fluid was 36.19 nm.2. Fe_3O_4 magnetic nanoparticles were prepared by the co-precipitation of Fe~(3+) and Fe~(2+) with surfactant. Thereafter, to enhance the compatibility between the magnetic Fe_3O_4 nanoparticles and water, an effective surface modification method was developed by grafting acrylic acid onto the nanoparticles surface. The effects o…
Key words: Fe_3O_4; nanoparticles; surface modification; grafting polymerization; water-base; magnetic fluid

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