Core/Shell Polystyrene/Magnetite Hybrid Nanoparticles Fabricated by Pickering Emulsion Polymerization and Their Magnetorheological Response

Soft-magnetic polystyrene (PS)/Fe3O4 core/shell composite nanoparticles are fabricated by surfactant-free Pickering emulsion polymerization using Fe3O4 nanoparticles as a solid stabilizer. The morphology of the synthesized PS/Fe3O4 particles consisting of a PS surface coated with Fe3O4 nanoparticles is examined by scanning electron microscopy and transmission electron microscopy. The thermal properties of Fe3O4 and PS/Fe3O4 are examined by thermogravimetric analysis, while the chemical bonding and composition of the nanocomposite are characterized by Fourier transform infrared spectroscopy and X-ray diffraction. The magnetorheological (MR) properties of the PS/Fe3O4 composite nanoparticles dispersed in silicone oil are analyzed using a rotational rheometer under an external magnetic field. The PS/Fe3O4-based MR fluids exhibit typical MR properties and a lower density compared to Fe3O4 nanoparticles, indicating the improved dispersion stability of the MR fluid compared to that of the Fe3O4 nanoparticle-based MR fluid.