Polyaniline based Composite for Gas Sensors

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In this research work, we have demonstrated the synthesis, spectroscopic characteristics, thermal behaviour and DC conductivity of a few nanostructured composites, substituted conducting polymers (ICPs) and composites of ICPs. The physical properties of aforementioned composites are significantly changed by the doping with HCl, H2SO4, HNO3, H3PO4, or acrylic acid. The charge transport properties of these polymeric materials have been studied in detail because of their potential application in gas sensors. In the current work, varieties of conducting polymer based materials such as PANI-ES/Cloisite 20A nanostructured composite, acrylic acid (AA) doped PANI polymer, N-substituted conducting polyaniline polymer, DL−PLA/PANI-ES composites, poly methyl methacrylate (PMMA) based polyaniline composite, and inorganic acid doped polyaniline are sucessfuly synthesized using aniline/aniline hydrochloride as precursors in acidic medium. Particularly, AA based synthesised PANI polymer was found with higher solubility The spectroscopic, thermal stability, enthalpy of fusion, room temperature DC conductivity and temperature dependent DC conductivity measurements with and without magnetic was carried out with as-synthesized materials. The FTR/ATR−FTIR spectra indicated the presence of different functional groups in the as-prepared composite materials. The UV−Visible absorption spectroscopic analysis showed the presence of polaron band suggesting PANI-ES form. The Room temperature DC conductivity, temperature variation DC conductivity (in presence and absence of magnetic field), and magnetoresistance (MR) of as-prepared conducting polyaniline based were analysed. The highest room temperature DC conductivity value was obtained from H2SO4 doped based composite materials and all prepared conductive composites were followed ohms law. The low temperature DC conductivity was carried out in order to study the semiconducting nature of prepared materials. The Mott type VRH model was found to be well fitted the conductivity data and described the density of states at the Fermi level which is constant in this temperature range. From MR plots, a negative MR was observed, which described the quantum interference effect on hopping conduction. We discuss different gas analytes i.e., NO2, LPG, H2, NH3, CH4, and CO of conducting polymer based materials.