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An in situ chemical polymerization method was applied in order to prepare polyaniline-multiwalled carbon nanotube (PANI-MWCNT) composites with different concentrations of MWCNT. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, optical absorption and photoluminescence analyses of the composites were performed to investigate the structural, morphological and optical properties of the composites. Electrical transport properties of different PANI-MWCNT composites were investigated in the temperature range 77 K T 300 K in the presence and also in the absence of a magnetic field up to 1 T. The dc resistivity of the composites follows Mott's variable range hopping theory. Two different slopes have been observed in temperature variation of resistivity, which occurs due to the presence of MWCNT in the polymer matrix. The magnetoconductivity of the samples at different temperatures is negative, which can be explained by the wavefunction shrinkage effect.

The present work describes the preparation of nanocomposites in which the multiwall carbon nanotubes (MWCNT) have been mixed with conducting polypyrrole (PPy) via an in situ chemical oxidative preparation method. To reveal their structural, morphological and thermal properties, the composites have been characterized by x-ray diffraction, field emission scanning electron microscope, Fourier transform infrared, thermogravimetric analysis respectively. Electrical transport and magnetotransport properties have been investigated in the temperature range 77-300K in presence as well as in absence of magnetic field up to 1Tesla. The conductivities of the composites are greater than that of pure polypyrrole. All the investigated samples follow Mott's variable range hopping (VRH) theory whereas the magnetic field dependent conductivity have been explained in terms of two opposite but simultaneously acting hopping effect-wave function shrinkage and forward interference effect.

Polyvinyl alcohol–polypyrrole–multiwall carbon nanotube composite polymer films have been synthesized by a chemical oxidative polymerization technique. Dielectric properties have been measured in the frequency range from 20 Hz to 1 MHz and in the temperature range 77 ⩽ T ⩽  300 K. Electric modulus vector analysis gives the presence of dielectric relaxation peaks for different composites from which the activation energies have been calculated.

The dc and ac electrical transport property of polyvinyl alcohol-multiwall carbon nanotubes composites has been investigated within a temperature range 77Յ T Յ 300 K and in the frequency range 20 Hz-1 MHz in presence as well as in absence of a transverse magnetic field up to 1 T. The dc conductivity follows variable range hopping model. The magnetoconductivity of the samples changes a sign from positive to negative with an increase in temperature which can be interpreted by the dominancy of the quantum interference effect over the wave function shrinkage effect. The ac conductivity follows a power law whereas the temperature dependence of frequency exponent s can be explained by correlated barrier hopping model. The dielectric behavior of the samples has been governed by the grain and grain boundary resistance and capacitance. The ac conductivity reduces with the application of magnetic field. Although the theoretical model to explain it, is still lacking, we may conclude that this is due to the increase in grain and grain boundary resistance by the application of magnetic field.

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We have synthesized composite of polyaniline nanotubes with lanthanum strontium manganite (La0.67Sr0.33MnO3) (LSMO) nanoparticles. Scanning electron microscopy, x-ray diffraction, Fourier transform infrared, and thermogravimetric analysis scans are done for morphological, structural, and thermal characterization of polyaniline-LSMO nanocomposite. Room temperature hysteresis loop shows ferromagnetic behavior of polyaniline-LSMO nanocomposite but with very low saturation magnetization. Overall pattern of temperature dependence of resistivity for polyaniline has been best-fitted with the form ln[ρ(T)]∝T−1/2. This may be attributed to quasi-one dimensional hopping and also tunneling between mesoscopic ferromagnetic metallic islands. Total resistivity due to grain and grain boundary reduces by application of magnetic field. Remarkable increase (∼73%) in magnetoresistance (MR) is obtained in these polymer coated LSMO compared to the without coated counterpart (16%). The MR% is found to increase with the increase in percentage of LSMO nanoparticles content in the composite. Temperature and magnetic field dependence of MR is observed. This nanocomposite can be used as a sensitive giant MR sensor.

Here, we report the synthesis of polyaniline-zirconium nanocomposite by chemical oxidative polymerization of aniline. Structural, thermal, and morphological properties of the samples are characterized by XRD, FTIR, TGA, SEM, and UV-Vis spectroscopy. Crystalline behavior of the nanocomposite has been obtained due to the presence of zirconium nanoparticles in polyaniline. FTIR analysis reveals the formation of polyaniline and changes to the structure of polyaniline due to the presence of zirconium nanoparticles. Granular morphology of the nanocomposite has been obtained from SEM micrographs and its conductivity has been increased due to the incorporation of zirconium nanoparticles. Temperature dependence of the resistivity has been fitted with ln [ρ(T)] ∝ T−1/4 which indicates three dimensional variable range hopping transport mechanism. ac conductivity follows the correlated barrier hopping transport mechanism. Some optical parameters like bandgap (Eg), peak transition energy (E0), and peak broadening parameter (C) are evaluated from real and imaginary dielectric functions. The value of the bandgap indicates the formation of a polaron lattice structure of the protonated emeraldine form of polyaniline.