Processible Nanostructured Materials with Electrical Conductivity and Magnetic Susceptibility:  Preparation and Properties of Maghemite/Polyaniline Nanocomposite Films

We here present a versatile process for the preparation of maghemite/polyaniline (γ-Fe2O3/PAn) nanocomposite films with macroscopic processibility, electrical conductivity, and magnetic susceptibility. The γ-Fe2O3 nanoparticles are coated and the PAn chains are doped by anionic surfactants of ω-methoxypoly(ethylene glycol) phosphate (PEOPA), 4-dodecylbenzenesulfonic acid (DBSA), and 10-camphorsulfonic acid (CSA). Both the coated γ-Fe2O3 and the doped PAn are soluble in common organic solvents, and casting of the homogeneous solutions gives free-standing nanocomposite films with γ-Fe2O3 contents up to ∼50 wt %. The morphology of the γ-Fe2O3 nanoparticles are characterized by transmission electron microscopy, UV−vis spectroscopy, and X-ray diffractometry. The γ-Fe2O3/PAn films prepared from chloroform/m-cresol solutions of DBSA-coated γ-Fe2O3 and CSA-doped PAn are conductive (σ = 82−237 S/cm) and superparamagnetic, exhibiting no hysteresis at room temperature. The zero-field-cooled magnetization experiment reveals that the nanocomposite containing 20.8 wt % γ-Fe2O3 has a blocking temperature (Tb) in the temperature region of 63−83 K.