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In this study, calcium titanate (CaTiO3) doped (0, 15, 25 and 35%) polyaniline (PANI) composites in the presence of dodecylbenzene sulphonic acid (DBSA) were successfully synthesized by the means of in-situ emulsion polymerization of aniline monomer. The structural, morphological and optical characterization of as-prepared composites were determined using X-ray diffraction (XRD), field effect scanning electron microscopy, Fourier-transform infrared spectroscopy, UV–vis analysis, and electronic conductivity was determined using two-point probe method. The structural analysis confirms that PANI–DBSA is amorphous, but sharp peaks present in XRD patterns in composites are of crystalline nature. The morphological study reveals efficacious integration of CaTiO3 particles into the PANI–DBSA matrix. Further, the integration of CaTiO3 remarkably reduced the optical bandgap (2.7–2.2 eV) by making composites with PANI–DBSA. Room temperature alternating current conductivity was found to obey universal power law and correlated barrier hopping was found most appropriate model to describe the sample's charge transport mechanism. With the increasing wt% of CaTiO3, the dielectric permittivity and loss both varied according to the interfacial polarization law of Maxwell–Wagner. Moreover, the I–V graphs showed augmented electrical conductivity of composites with an increase in CaTiO3 particle content than that of pure PANI–DBSA. This is a simple way by which PANI–DBSA/CaTiO3 composites having low optical bandgap, high electrical conductivity and permittivity may be fabricated for a widespread technological application. [ABSTRACT FROM AUTHOR]

In situ polymerization of aniline was carried out with calcium titanate, in order to synthesize polyaniline/calcium titanate composites by the chemical oxidation in the presence of ammonium persulfate as an oxidizing agent. To study the effect of calcium titanate on the properties of polyaniline (PANI), PANI/calcium titanate (CaTiO3) composites were synthesized with different weight percentages (15, 25, and 35 wt %) of calcium titanate. The structural and morphological analysis was carried out by XRD and SEM, while their electrical properties were studied by temperature-dependent dc conductivity. Thermal properties were also studied, and seebeck coefficient and thermoelectric power studies demonstrated a strong dependence on the weight percentage of calcium titanate in the pure polyaniline. The charge transport mechanism was investigated by temperature-dependent dc electrical conductivity measurements in the temperature range of 303–483 K. Further, an increase in dc conductivity was found on the inclusion of calcium titanate at all temperatures, and the most probable model of charge transport was found to be three-dimensional variable range hopping (3D-VRH) for pure polyaniline while switching to one-dimensional variable range hopping (1D-VRH) in the case of its composites with calcium titanate that has been interpreted in terms of linearization and straightening of polymer chains. The calcium titanate content not only influenced the electrical conductivity but the thermoelectric properties of the resulting composites as well. [ABSTRACT FROM AUTHOR]

In situ chemical polymerization method was used to synthesize the polyaniline (PANI) and polyaniline cadmium oxide (PANI-CdO) nanocomposites. The morphology and structure of pure PANI and PANI-CdO nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, whereas electrical properties were studied by dielectric, electric modulus and a.c conductivity. Various dopant-to-polymer ratios were used to investigate their effect on the characteristics of the synthesized samples. The SEM images exhibited granular as well as flaky structures of PANI and PANI-CdO nanocomposites. The XRD patterns revealed that pure PANI exhibits amorphous nature, while PANI-CdO nanocomposites exhibit polycrystalline nature. The crystallinity and intensity of (XRD) peaks of composite are enhanced by increasing CdO contents. The dielectric measurements show a decrease in dielectric constant, dielectric loss and a decrease in tangent loss with the increase in frequency and nearly constant values at higher frequencies, while the values of dielectric properties increase with the rise in temperature and doping concentration. The electric field modulus was used to analyze the relaxation behavior of the synthesized samples and found to be increased with frequency and decreased with the temperature and CdO concentration. The a.c conductivity was observed to increase with the increase in frequency and temperature for PANI and PANI-CdO composites. The changing behavior of the frequency exponent (S) at various temperatures was analyzed to observe different conduction mechanisms, and a correlated barrier hopping model (CBH) was found to be observed in PANI-CdO composites as well as in pure PANI. The Log a.c conductivity decreases versus the inverse of temperature and with increase in frequency that confirms that the hopping mechanism is the dominant charge transport mechanism. [ABSTRACT FROM AUTHOR]

Dodecylbenzenesulfonic acid (DBSA) doped polyaniline and carbon black (CB) composites (PANI-DBSA/CB) were synthesized by in-situ polymerization of aniline in the aqueous dispersion of carbon black (CB) in the presence of ammonium persulfate (APS) as an oxidant. Various composite samples with varying amounts of CB (1 wt% and 2 wt%) were synthesized and were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD studies confirmed the formation of the well-organized and semi-crystalline structure of the composites. SEM analysis revealed the increase in grain size and the granular structure of the synthesized composites. DC conductivity was measured in the temperature range from 300 K to 393 K using two probe methods. An increase in DC conductivity was found on the inclusion of carbon black at all temperatures and the most probable model of charge transport was found to be three-dimensional variable range hopping (3D-VRH). As the concentration of CB in the composites increased, activation energy was found to be decreased. The density of states, hopping length, and hopping energy were calculated, respectively, and were found to be influenced by CB incorporation. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane/polyaniline-based stretchable strain sensors were prepared via in situ polymerization of aniline in the TPU solution in the form of thin films. The sensors where characterized for morphological and thermal properties, mechanical hysteresis and cyclic piezoelectric performance. Thermogravimetric analysis showed blends to be thermally stable up to 230 °C. Electrical conductivity increased up to 30 wt% of Ani.DBSA loading after which a decline was observed due to reduced conversion of aniline monomer to polyaniline. Piezo-resistive measurements also showed a decrease in electrical conductivity upon stretching due to disconnection mechanism between Ani.DBSA particles. The cyclic piezo-resistive properties were evaluated at a strain of 10%. The sensors showed a gauge factor of 2.59. The dispersion and distribution was uniform at all levels of Ani.DBSA loading as visualized by SEM analysis. Beside uniform dispersion, SEM analysis also revealed polyaniline chains connecting with the polyurethane matrix which increases its conductivity. Hence, the proposed sensors can be employed as flexible strain sensors. [ABSTRACT FROM AUTHOR]

In this study, the cadmium selenide quantum dots/polyaniline nanocomposites were prepared by in-situ polymerization technique and they were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The surface morphology was studied by scanning electron microscopy. The electrical and dielectric properties were investigated by using 4-probe mechanism and LCR meter respectively. The increase in dielectric constant was observed with the increase of quantum dots content in the nanocomposites. The frequency dependent AC conductivity followed the universal power law. The temperature dependent DC conductivity was found to be a typical for a semiconducting behavior following Mott's 1D variable range hoping model. [ABSTRACT FROM AUTHOR]

Conducting polymer nanocomposites of polyaniline with ZnNiCrFeO nanoparticles were synthesized by in situ chemical polymerization. The sample properties were studied by X-ray diffractometer, Fourier transform infrared spectroscopy and transmission electron microscopy. Above techniques confirmed the formation of two phase system. The dielectric permittivity, magnetic permeability and microwave absorption properties of the polyaniline-ferrite composites were carried out in the 4-18 GHz frequency range. Conductivity was found to have an impact on microwave absorbing properties. The composite with 25 wt% of ferrite content has shown better absorption properties with wide band gap in whole Ku band. This value of absorption suggests that this composite can be used as a potential radar absorbing material. [ABSTRACT FROM AUTHOR]

Two organic–inorganic hybrid films of intrinsically conducting polymer; polyaniline and cadmium selenide quantum dots were prepared. One by layer-by-layer deposition of polyaniline and cadmium selenide films on PEDOT-PSS/ITO coated glass substrate (ITO/PEDOT-PSS/PANI/CdSe) and other by depositing polyaniline-cadmium selenide quantum dots composite film on the same substrate (ITO/PEDOT-PSS/PANI-CdSe) using spin coating technique. Pure polyaniline, cadmium selenide quantum dots and their composites thus obtained were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV/VIS/NIR absorption spectroscopy. The surface morphologies were studied by Scanning Electron Microscopy (SEM). The diode performance parameters were compared and contrasted for the two devices obtained by different deposition routes. J – V characteristics of these devices showed a rectifying contact with Al metal, however with variation in performance parameters like barrier height, ideality factor and reverse saturation current the ITO/PEDOT-PSS/PANI-CdSe/Al device exhibited better diode performance as compared to ITO/PEDOT-PSS/PANI/CdSe/Al device. [ABSTRACT FROM AUTHOR]

Composites of polyaniline with yttrium oxide (YO) nanoparticles have been prepared by chemical polymerizations method by increasing the weight percentage of yttrium oxide. X-Ray diffraction (XRD) and Fourier Transform Infrared Spectra (FTIR) were used to characterize the composites. XRD and FTIR pattern indicate that Polyaniline (PANI) is intercalated into the layers of YO nanoparticles successfully by in situ polymerization and therefore the degree of crystallinity increases due to crystalline of yttrium oxide nanoparticles. The scanning electron micrographs (SEM) also confirm the formation of dual phase of platelet as well as of flaky structure in PANI-YO. Temperature dependant DC conductivity showed three dimensional variable ranges hopping (3D VRH) model. Activation energy, density of states and hopping length are calculated and found to be influenced by intercalating PANI into the layers of YO clay. [ABSTRACT FROM AUTHOR]

Composites of polyaniline with yttrium oxide (YO) have been synthesized by chemical polymerization method. The structural properties of synthesized Polyaniline (PANI) and PANI/YO were studied by X-ray diffraction (XRD) analysis. XRD pattern indicate that PANI is intercalated into the layers of YO successfully and therefore the degree of crystallinity increases due to crystalline of YO. Fourier transform infrared (FT-IR) indicated that there is a strong interaction between PANI and YO. Electronic properties (Dielectric and Conductivity) of PANI and PANI/YO composite have been investigated between frequency ranges of 1 MHz and 3.0 GHz. Higher dielectric constants and dielectric losses of PANI/YO composites than those of Synthesis PANI were found. As the content of YO increased, the dielectric constant and loss also increased. The value of dielectric constant (ε/) for all PANI/YO composite is very high at low frequency but decreases with the increases of frequency. PANI/YO composite materials with high dielectric constants are highly desirable for use in charge-storage devices. [ABSTRACT FROM AUTHOR]