LAUSR

Abstract In this work, a polystyrene/polyaniline powder of core-shell structure was prepared by chemical polymerization of aniline, using tartaric acid as a dopant and ammonium persulfate as an oxidizer in presence of polystyrene. The matrix effect on the electrical properties of pure polyaniline was studied by means of dielectric relaxation spectroscopy (DRS) and electron paramagnetic resonance (EPR) technique at room temperature. AC conductivity and dielectric permittivity of the polystyrene/polyaniline were investigated in the frequency range of 10−1 - 106 Hz. The doped polyaniline showed a DC conductivity of 10−5 S/cm. Its incorporation in a polystyrene matrix lowered the conductivity of the mixture up to 10−7 S/cm. This value remains acceptable for semi conductive applications. EPR characterization confirmed this behavior, it gave g-factor values equal to 2.0046 and 2.0093 for polyaniline and polystyrene/polyaniline respectively, close to the free electron g-factor value (2.0023), suggesting that the resonance comes from the delocalized electrons in the main chain of polyaniline. High dielectric constants were obtained for both polyaniline and polystyrene/polyaniline allowing their use as high k-dielectrics. The composite material showed two different relaxation processes. The first one may originate from the electrode polarization while the second is associated to the bulk relaxation of charge carriers.