Abstract
Poly(methyl methacrylate) (PMMA) microspheres several tens micrometers in diameter, containing highly dispersed sub-micron sized magnetite (Fe3O4) particles, were successfully prepared via an emulsion polymerization process. Both oleic acid and sodium olate acted as suitable agents for high dispersion of the Fe3O4 particles in the starting monomer solution (MMA). Spherical PMMA particles encapsulating 65–72 mass % (30–38 vol %) of the Fe3O4 were obtained. The magnetic properties of the Fe3O4 loaded PMMA microspheres depended on the amount of Fe3O4 present in the resultant microspheres. The saturation magnetization and coercive force of the microspheres were 49–63 emu·g−1 and 162–170 Oe, respectively. The rate of an increase in temperature by heat generated from an agar phantom dispersed with a microsphere sample was 1 K·min−1 under an alternating magnetic field (100 kH, 300 Oe). This material is expected to be utilized as a thermal seed for hyperthermic treatment of deep-seated cancers in our bodies using a gap-type alternating current field apparatus in combination with a prospective drug delivery system.
