LAUSR

Magnetic poly(methyl methacrylate) (PMMA)/Fe3O4 composite nanoparticles were fabricated by Pickering emulsion polymerization using nano-sized iron oxide (Fe3O4) particles as a solid stabilizer that had been synthesized initially from a hydrothermal process. High-resolution scanning electron microscopy was applied to characterize the morphology of the materials. Fourier transformation infrared spectroscopy confirmed the chemical structure of both pure Fe3O4 and PMMA/Fe3O4 composites. The magnetic properties and atomic and molecular structure of a crystal of the materials were examined by vibration sample magnetometry and X-ray diffraction, respectively. The magnetorheological (MR) features of both pure Fe3O4 and PMMA/Fe3O4 nanoparticles dispersed in mineral oil under a magnetic field were characterized by a rotational rheometer. The dynamic yield stress was higher than the elastic stress under external magnetic field. The PMMA/Fe3O4 composite-based MR fluid showed good dispersion stability, while exhibiting typical MR characteristics for the applied magnetic field dependent yield stress with a slope of 1.5.