Synthesis of copper chloride and cobalt chloride doped polyanilines and their magnetic and alternating‐current transport properties

Abstract Polyaniline (PANI) was synthesized by the well‐known oxidative polymerization of aniline with ammonium peroxodisulfate as the oxidant. The morphological, structural, thermal, optical, magnetic, and electrical properties were characterized with scanning electron microscopy, X‐ray diffraction, Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, room‐temperature magnetic measurements, and low‐temperature electrical transport measurements by the standard four‐probe method. Greater thermal stability and crystallinity were observed in doped PANI versus pure PANI. Magnetic measurements showed that the magnetic susceptibility was field‐dependent. Positive and negative susceptibility values were observed. This may have been due to the interactions of magnetic ions among interchains or intrachains of the polymer matrix. The alternating‐current (ac) conductivity was measured in the temperature range of 77–300 K in the frequency range of 20 Hz to 1 MHz. The frequency‐dependent real part of the complex ac conductivity was found to follow the universal dielectric response: σ′( f ) ∝ f s [where σ′( f ) is the frequency‐dependent total conductivity, f is the frequency, and s is the frequency exponent] The trend in the variation of the frequency exponent with temperature corroborated the fact that correlated barrier hopping was the dominant charge‐transport mechanism for PANI–CoCl 2 . An anomalous dependence on temperature of the frequency exponent was observed for PANI–CuCl 2 . This anomalous behavior could not be explained in terms of existing theories. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010