Magnetic poly(glycidyl methacrylate) microspheres containing maghemite prepared by emulsion polymerization

Magnetic poly(glycidyl methacrylate) (PGMA) microspheres were prepared by emulsion polymerization of glycidyl methacrylate (GMA) in the presence of (carboxymethyl)dextran (CM-dextran)-stabilized iron oxide colloid. Scanning electron microscope (SEM) and transmission electron microscope (TEM) microstructural studies revealed a spherical shape of the particles in 72-84 nm size range. Magnetic iron oxide nanoparticles (< 10 nm) were partly inside the PGMA microspheres and partly adhering to the microsphere surface. X-ray phase analysis revealed spinel structure of the iron oxide particles. According to the Mossbauer spectra, iron oxide consisted mainly of the maghemite phase. Temperature evolution of the spectra completed by the magnetization measurements confirmed superparamagnetic behavior at room temperature and the transition to the ordered state at lower temperatures. As expected, saturated magnetization increased with increasing content of the maghemite phase in the magnetic PGMA microspheres. (C) 2006 Elsevier B.V. All rights reserved.