A facile two-step modifying process for preparation of poly(SStNa)-grafted Fe3O4/SiO2 particles

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 Stöber 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 photoelectron 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.

Fig. 2b shows TEM images of silica-coated Fe3O4 particles. The magnetic silica particles with well-defined core/shell structures were rather monodisperse, even though silica shells have trapped more than one magnetic core. The Fe3O4/SiO2 particles used in this case for the production of composite particles had an average diameter of 70±10 nm obtained by TEM images.Figure optionsDownload as PowerPoint slide