Magnetite Embedded Mini-Emulsion Polymerized Polystyrene Particles and Their Magnetorheology

Novel Fe 3 O 4 -encapsulated polystyrene (PS) hybrid particles were synthesized by a new preparation route involving mini-emulsion polymerization. A ferrofluid of oleic acid-coated Fe 3 O 4 in octane was obtained initially, and then emulsified by an ultra-sonication process with sodium dodecyl sulfate as a surfactant. The suspension composed of the obtained Fe 3 O 4 clusters was mixed with a styrene monomer, and the resulting Fe 3 O 4 clusters served as templates for mini-emulsion polymerization. The embedded structure and uniform size of the fabricated Fe 3 O 4 /PS particles were examined by transmission electron microscopy, while their thermal properties, chemical structure, and magnetic properties were confirmed by thermogravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometry, respectively. The magnetorheological (MR) characteristics of the resulting particles dispersed in silicone oil were tested using a rotational rheometer. The fluid composed of Fe 3 O 4 /PS particles exhibited typical MR fluid behavior under applied magnetic fields.