A facile two-step modifying process for preparation of poly(SStNa)-grafted Fe3O4/SiO2particles

This article reports the synthesis of the poly(sodium 4-styrenesulfonate)-grafted Fe3O4/SiO2 particles via two steps. The first step involved magnetite nanoparticles (Fe3O4) homogeneously incorporated into silica spheres using the modified Stober method. Second, the modified silica-coated Fe3O4 nanoparticles were covered with the outer shell of anionic polyelectrolyte by surface-initiated atom transfer radical polymerization. The resulted composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive microscopy (EDS), Fourier transform-infrared (FT-IR), thermogravimetric analysis (TGA), X-ray photoclectron spectroscopy (XPS) and vibration sample magnetometer (VSM). The XRD results indicated that the surface modified Fe3O4 nanoparticles did not lead to phase change compared with the pure Fe3O4. TEM studies revealed nanoparticles remained monodisperse. The detection of sulfur and sodium signals was a convincing evidence that sodium 4-styrenesulfonate was grafted onto the surface of the magnetic silica in XPS analysis. Finally, super-paramagnetic properties of the composite particles, and the ease of modifying the surfaces may make the composites of important use in mild separation, enzyme immobilization, etc. (C) 2007 Elsevier Inc. All rights reserved.