Magnetic and conducting Fe3O4-polypyrrole nanoparticles with core-shell structure

Magnetic and conducting Fe3O4-polypyrrole nanoparticles with core-shell structure were prepared in the presence of Fe3O4 magnetic fluid in aqueous solution containing sodium dodecylbenzenesulfonate (NaDS) as a surfactant and dopant. Both the conductivity and magnetization of the composites depend strongly on the Fe3O4 content and the doping degree. With increase of Fe3O4 content in the composite, the conductivity at room temperature decreases, but the saturated magnetization and coercive force increase. Transmission electron microscopy (TEM) images of Fe3O4 and Fe3O4-polypyrrole particles show almost spherical particles with diameters ranging from 20 to 30 and 30 to 40 nm, respectively. The thermal stability of Fe3O4-polypyrrole composites is higher than that of pure polypyrrole. Studies of IR, UV-visible and X-ray photoelectron spectroscopy (XPS) spectra suggest that the increased thermal stability may be due to interactions between Fe3O4 particles and polypyrrole backbone. (C) 2003 Society of Chemical Industry.