Unique properties of polyaniline in the presence of applied magnetic field and ferric chloride

Fe-contained polyaniline (abbreviated as PANI–Fe) was prepared by chemical oxidation of aniline with ammonium peroxydisulfate oxidant in 0.5 mol dm−3 HCl and an adequate content of FeCl3·6H2O solution in the presence of an applied magnetic field at room temperature. The X-ray photoelectron spectroscopy (XPS) and UV–vis and FTIR spectra suggest that there is an interaction between FeCl3 and PANI chains, but PANI–Fe backbone is essentially identical with that of parent polyaniline. The electron paramagnetic resonance (EPR) spectrum shows that there were unpaired electrons in PANI–Fe synthesized in the presence of an applied magnetic field, the spin density and the conductivity of which are 7.308 × 1020 spins g−1 and 0.891 S cm−1, respectively. The plot of magnetization (M) vs. the applied magnetic field (H) displays that the PANI–Fe possesses soft ferromagnetic behavior at room temperature. The results of cyclic voltammogram show that the PANI–Fe film is of excellent electrochemical activity.