Formation Of Polyaniline Research Articles

Simultaneous Oxidation and Doping of Aniline to Polyaniline by Oxidative Template: Electrochemical Performance in Supercapacitor

Polyaniline salts containing sulfuric acid and cetyltrimethylammonium sulfate dopants were prepared by aqueous (PANI-Aq), emulsion (PANI-Em), and interfacial (PANI-In) polymerization pathways using cetyltrimethylammonium peroxodisulfate as an oxidative template. Formation of polyaniline was confirmed from infrared and X-ray diffraction spectral results. Value of conductivity (15 S cm−1) of the polyaniline salt prepared by emulsion polymerization pathway was higher with that of the conventional polyaniline salt. PANI-Aq, PANI-Em, and PANI-In showed layered, flower petals, and nanorod and flower petals morphologies, respectively. These polyaniline salts were used as electrode in supercapacitor. Specific capacitance of PANI-Em, PANI-Aq, and PANI-In were 520, 484, and 474 F g−1, which were higher than the conventional PANI-H2SO4 salt (390). Energy density was 26, 24.2, and 23.6 Wh kg−1, respectively at a power density of 120 W kg−1. After 3000 charge-discharge cycles, retention in the specific capacitance values of polyaniline salts was 86% (PANI-Em), 85.4% (PANI-Aq) and 76.1% (PANI-In).

Improved electrochemical performances of polyaniline by graphitized mesoporus carbon: Hybrid electrode for supercapacitor

ABSTRACTIn this work, graphitized mesoporus carbon (GMC) was used to increase the specific capacitance and cycle stability of polyaniline (PANI). Hybrid material of polyaniline‐graphitized mesoporus carbon (GMCP) was prepared by in situ chemical polymerization of aniline in presence of sulphuric acid using ammonium persulfate oxidant with various amounts of GMC. Formation of hybrid sample was confirmed from X‐ray diffraction, and the composite sample was stable up to 250°C. Morphology, crystalline nature, and electrochemical performance of GMCP were compared with that of its individual components, GMC and PANI. GMC showed particle morphology and PANI showed nanofiber morphology. GMCP2 composite showed nanofibrous form of PANI grown on GMC (spherical form) along with PANI nanofibers. Higher crystallinity was obtained for GMCP than that of PANI. Cycling stability of GMCP2 was carried up to 12,000 cycles at 1200 W kg−1 and the retention capacitance was 66% of its original capacitance of 243 F g−1. With the same power density, GMC showed less capacitance value of 53 F g−1 with 92% retention and PANI showed capacitance of 187 F g−1 and it underwent 1500 cycles only. Higher supercapacitor performance was obtained for GMCP composite compared to that of its components, PANI and GMC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42540.

Polyaniline and polypyrrole/TiO2 nanocomposite coatings on Al1050: electrosynthesis, characterization and their corrosion protection ability in saltwater media

Polyaniline (PANI), polypyrrole (PPy) nanofilms, PANI/TiO2 and PPy/TiO2 nanocomposites were synthesized electrochemically on Al1050 electrode. The formation of PANI and PPy nanofilms and PANI/TiO2 and PPy/TiO2 nanocomposites was characterized by Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), UV–visible absorption spectroscopy (UV–Vis), scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX), and electrochemical impedance spectroscopy (EIS). The comparative morphologic, spectroscopic and electrochemical properties of the prepared PANI and PPy nanofilms and nanocomposites were investigated in this study. The effectiveness of polymer and nanocomposite films in preventing the corrosion of Al1050 was tested in 3.5 % NaCl solution. For corrosion tests, anodic polarization curves and EIS were used to investigate their corrosion protection capability in saltwater solution. The highest, low frequency capacitance values were obtained as CLF = 60.76 and 12.8 mF cm−2 for PANI/TiO2 and PPy/TiO2 nanocomposites, respectively. The results of these studies revealed that the corrosion protection efficiency (PE) of the PANI/TiO2 (PE = 97.2 %), PPy/TiO2 (PE = 97.4 %) nanocomposites coated on Al1050 electrode was higher than that of PANI (PE = 96.4 %), PPy (PE = 94.9 %) and uncoated Al1050 electrodes. These nanocomposites can be used in airplanes, space technology, automobiles, electronics, and building sectors, as well.

Study of room temperature LPG sensing behavior of polyaniline thin film synthesized by cost effective oxidative polymerization technique

Polyaniline thin films doped with an inorganic acid were deposited on glass substrate using simple and cost effective oxidative polymerization technique. As- synthesized thin film of polyaniline was studied with dif- ferent characterization techniques. The formation of polyaniline on glass substrate was confirmed by X-ray diffraction and UV spectroscopy. Surface morphological investigation was performed using scanning electron mi- croscopy. Gas sensing behavior of polyaniline thin film was studied by I-V measurements before and after lique- fied petroleum gas (LPG) exposure at room temperature, based on change in electrical resistance. The observed re- sult shows polyaniline thin film sensor is efficient for LPG detection at room temperature.

Concurrent genesis of color and electrical conductivity in leathers through in‐situ polymerization of aniline for smart product applications

We present a simple method to produce self‐colored and conducting leathers using in‐situ polymerization of aniline with ammonium persulfate as oxidant and hydrochloric acid as dopant. The structural and morphological features of treated leathers were examined using Fourier transformed infra‐red spectroscopy, X‐ray diffraction and scanning electron microscopic analyses. Results suggest the deposition of conducting emeraldine salt form of polyaniline on the leather substrate rather than other poorly conducting states. We also show that the treated leathers are bluish green through reflectance measurements thereby suggesting that the use of toxic and expensive dyes can be avoided for coloration process. Further, we demonstrate that a maximum electrical conductivity of 0.15 S/cm is obtained for the leather treated with optimal experimental conditions, which aids its application to operate touch‐screen devices. Copyright © 2015 John Wiley & Sons, Ltd.

Cathodic deposition of copper on polyaniline-coated textiles from a citrate bath: effects of electroplating conditions

Copper electrodepostion on polyaniline (PANI)-covered poly(ethylene terephthalate) (PET) textiles was realized galvanostaticly in a plating solution containing sodium citrate. Electrochemical behaviors of Cu deposition on PANI/PET electrodes in citrate baths were studied by measuring the cathodic polarization curves. Electroplating conditions such as concentrations of copper sulfate, sodium citrate and sodium sulfate, pH value, current density as well as the concentration ratio of oxidation/monomer for PANI formation were determined by comparing the polarization curves and the current efficiency results. The surface morphologies of Cu/PANI/PET formed under the different current density were evidenced by scanning electron microscopy. In addition, the conductivity of the synthesized films was also measured with a four-probe method and the lowest sheet resistance of 100 mΩ/sq was presented at 60–80 mA cm−2, in which the maximum current efficiency reached up to 85 %. The deposition mechanism that the reductions of copper ions and PANI layers occurred in parallel, and the growth of copper crystals performed at the polymer surface were deduced.

Synthesis, characterization and dielectric investigation of ZnO-doped polyaniline nanocomposites

Polyaniline (PANI) synthesized through the in situ polymerization method and its composites with zinc oxide nanoparticles loaded in various weight percentages were studied. The formation of PANI and its composites was characterized using different characterizing tools, and detailed analysis was done to investigate the structural and morphological properties of the composites. The presence of the vibration band of the metal oxide and other characteristic bands of the composites, as characterized via Fourier transmission infrared spectroscopy, confirmed the synthesis of the polymer nanocomposites. The X-ray diffraction patterns of the nanocomposites revealed their polycrystalline nature. The dielectric responses of PANI and the ZnO-doped PANI composites were investigated within the frequency range of 20 Hz to 1 MHz. The dielectric constant of the ZnO-doped PANI composite was found to be higher than that of the pure PANI. The value of the dielectric constant decreased with increasing frequency, and it became constant at higher frequencies, which is attributed to the interfacial polarization.

Influence of the polyaniline structure on the properties of epoxy compounds and materials

Rheological properties of epoxy compounds containing pernigraniline and emeraldine forms of polyaniline were studied. The emeraldine form of polyaniline catalyzes the curing of epoxy compounds. The influence of the emeraldine and pernigraniline forms of polyaniline on the glass transition point of epoxy polymeric materials was determined. The elastic and deformation properties of the epoxy polymeric materials were studied. At up to 0.28 wt % content of the emeraldine form of polyaniline, the elastic modulus and ultimate strength increase. Introduction of the pernigraniline form of polyaniline leads to a decrease in the elastic modulus and to an insignificant increase in the ultimate strength of the epoxy polymeric materials.

Preparation and Electrical Characterization of Poly(Aniline) NanoClay Composites

AbstractIn this work, synthesis and characterization of composite materials based on NanoClay(NC) and boric acid doped PolyAniline (PANI) is studied. PANI was successfully incorporated into NC to form PANI-NC composites. The resulting organic-inorganic hybrid material, PANI-NC was characterized by various physicochemical techniques. Formation of PANI inside the clay tactoid has been confirmed by X-ray diffraction studies (XRD), scanning electron microscope (SEM) and FT-IR. Also, conductivity and physical properties of the PANI-NC composites were investigated.

Interaction of Ion Iron(II) with Polyaniline Observed by Infrared Spectroscopy, X-ray and Mössbauer Spectroscopy

This study investigated the interaction of Fe(II) ions with esmeraldine salt form of polyaniline (PANI -ES). Treatment of the aniline with ammonium persulfate in an acidic medium generated the polymer, which was doped with iron ion through the addition of the salt Fe(NH4)2(SO4)2·6H2O in amounts equimolar a room temperature. Xray diffraction, infrared and Mossbauer spectroscopies were used to characterize the doped polymer. Through the set of spectroscopic results it was possible to confirm the formation of PANI-Fe (II) complex and that these ions interacted with the benzenoids nitrogen atoms of the polymer chain.

Preparation and characterization of a new polyaniline salt with good conductivity and great solubility in dimethyl sulfoxyde

In this study, we propose a novel conducting and soluble polyaniline salt prepared by chemical polymerization in the presence of new doping agent (IAs). This last is prepared by sulphonation of itaconic acid (IA) with concentrated sulphuric acid in THF. The obtained doped polyaniline (PANI-IAs) is extremely soluble in dimethyl sulfoxyde (DMSO) at room temperature, in which the solubility reach 44 mg mL-1. The conductivity measurement of doped polyaniline powder precipitated in THF as dispersing medium gave a value of 0.13 S cm-1 when the emeraldine base form of polyaniline is fully protonated. The polyaniline salt sample is characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction, UV-Visible spectra and FTIR spectra.

Development of Electrospun Polyaniline/ZnO Composite Nanofibers for LPG Sensing

In this paper we report the highly sensitive at low temperature and low concentration of liquefied petroleum gas (LPG) sensor based on D-Camphor-10-Sulphonic acid (CSA) doped Polyaniline/Polyethylene Oxide (PANI/PEO) and PANI/ZnO/PEO nanofibers fabricated by electrospinning technique. Nano-sized particles of zinc oxide (ZnO) were synthesized using sol-gel method. The emeraldine base form of polyaniline (PANI) and PANI/ZnO synthesized by chemical oxidative polymerization were treated with CSA for better solubility and conductivity and then blended with PEO solution to get nanofibers using electrospinning. The morphology and structure of electrospun nanofibers of CSA doped PANI/PEO and PANI/ZnO/PEO were investigated by SEM, UV-VIS, FTIR and XRD. The change in electrical resistance of CSA doped PANI/PEO and PANI/ZnO/PEO for 1000ppm of LPG was measured. Both the samples showed a rapid and reversible resistance change upon exposure to LPG gas at 1000ppm concentration. Maximum sensitivity was achieved at 36°C for PANI/ZnO/PEO indicating suitability of nanofibrous PANI/ZnO/PEO towards LPG sensing as compared to pure ZnO and PANI.

Time resolved excitation dynamics in emeraldine base

Using femtosecond pump–probe transient absorption spectroscopy (wavelengths 330–800nm), we observed and explained excited state, charge transfer and polaron state dynamics in emeraldine base form of polyaniline in dimethyl sulfoxide solution. The excited state created by a pump pulse (700nm) in the quinoid absorption Q-band loses its initial symmetry by subsequent energy transition to a charge transfer state within 50fs. The hot charge transfer state either recombines non-radiatively into the ground state with decay time constant 0.55ps or transfers into a relaxed state corresponding to the relaxed phenyl geometry during ca 2.1ps. This relaxed state shows a prolonged lifetime of about 6.5ps before its recombination to the ground state. However, a small amount of long-lived polarons with lifetime of about 2ns in air and with lifetime longer than 6ns in the solution bubbled with dry N2 was detected.

Effects of potentiodynamic electropolymerization parameters on electrochemical properties and morphology of fabricated PANI nanofiber/graphite electrode

In this study, aniline nanofibers were fabricated through cyclic voltammetry electropolymerization on graphite electrode in the acidic solution of Aniline, in two different conditions. In the first condition aniline was electropolymerized in a potential range from −0.2 to 1V and at different scan rates, while in the second condition; electropolymerization was done at a fixed scan rate of 25mVs−1 and with different switching potentials. The effect of scan rate and switching potential on electrochemical properties and the morphology of produced polyaniline film was investigated by different electrochemical tests such as cyclic voltammetry, electrochemical impedance spectroscopy, and also scanning electron microscopy. The electrochemical investigations indicated that an optimum condition of 25mVs−1 scan rate and a −0.2 to 1V potential range can be reached where electropolymerized polyaniline could be at its peak of electroactivity, electrical and ionic conductivity and apparent diffusion coefficient (D), which is ideal for electrocatalytic applications. The SEM micrographs also confirm the formation of polyaniline with nanofibrous morphology at this optimum condition.

The first report of polymerization and characterization of aniline bearing chiral alkyl group on ring via covalent bond; poly[(±)-2-(sec-butyl)aniline

A chiral alkyl substituted of polyaniline derivative, poly[(±)-2-(sec-butyl)aniline] was successfully synthesized by interfacial and conventional oxidative chemical polymerization. Both distilled and dark monomers (undistilled) were used in polymerization. The polymers were characterized in details by several techniques, proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR), high resolution mass spectroscopy (HRMS), Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis) spectroscopy, elemental analysis (CHNS) and X-ray diffraction (XRD) as well as gel-permeation chromatography (GPC) and scanning electron microscopy (SEM) images. Conductivity of polymers was also measured. Spectroscopic studies have proved the formation of polymer and confirm the pernigraniline form of polyaniline. Mass spectra of polymers synthesized were studied exactly and prove the presence of both amine and iminium nitrogen as well as counter ions of Cl−, HSO4− and SO42−. Size of polymer particles is considerably smaller by interfacial polymerization. Polymers show semi-crystalline structure in XRD analysis. More crystalline structure and conductivity gained from interfacial polymerization. Molecular weights of polymers were lower in comparison with polyaniline according to GPC results. The effect of neutral salt (LiCl) was studied on molecular weight.

Pressure-Induced Reactivity in the Emeraldine Salt and Base Forms of Polyaniline Probed by FTIR and Raman

This report presents the influence of the morphology on the pressure-induced reactivity of the doped (PANI-ES) and dedoped (PANI-EB) forms of polyaniline using Raman and FTIR techniques. Our PANI-EB FTIR spectroscopy data showed an intensity exchange among characteristic bands of the quinoid and benzoic segments above 9 GPa, suggesting a specific coupling reaction between adjacent quinoid rings. The reaction kinetic was followed, and the results showed a dependence of the rate constant with pressure, as well as the activation volume, presented an inversion from negative to positive at 13 GPa, suggesting that steric factors have a role in the reactivity of the species. Raman spectra of PANI-ES showed a broadening and a blue shift of the bands as the pressure increases preceding the almost complete amorphization of the polymer; after decompression, some minor spectral changes were observed, suggesting the occurrence of the dedoping and cross-linking reactions in less extension than PANI-EB.

A facile method for the sensing of antioxidants based on the redox transformation of polyaniline

Polyaniline (PANI) is one of the most studied conducting polymers. It could adopt a number of chemical forms depending on the redox states of the assay solution. It was observed that the emeraldine base form of PANI could be reduced by common antioxidants (such as glutathione and ascorbic acid), which resulted in clear changes of the solution color and the UV–vis absorption spectra. In addition, it was observed that the fluorescence of CdTe quantum dots could be efficiently quenched by PANI, and the fluorescence quenching could not take place by the addition of antioxidants. The intensity of the quantum dots fluorescence could be directly related to the amount of antioxidant added to the assay solution, thus a sensitive fluorescent turn-on sensor for antioxidant was established. The detection limits for glutathione and ascorbic acid were estimated to be 50nM and 100nM, respectively. Our assay is simple, sensitive, and label-free, we envision it could facilitate the antioxidant sensing related applications.

Surface functionalization effects on structural, conformational, and optical properties of polyaniline nanofibers

Polyaniline nanofibers have been synthesized by dilute polymerization technique and functionalized with glutaraldehyde under acidic condition. The effects of surface functionalization of polyaniline nanofibers on their structural, conformational, and optical properties have been investigated using transmission electron microscopy (TEM), X-ray diffraction, UV–visible, infrared, and fluorescence spectroscopy. TEM and UV–vis spectroscopy results depict that fiber diameter is decreased from 35.66 to 31.04nm on functionalization. XRD analysis suggests increased doping of surface functionalized polyaniline nanofibers (SF-PNFs) than that of the pristine polyaniline nanofibers (PNFs). Evolution of fluorescence peak at 452nm in the fluorescence spectra and disappearance of absorption peak at 630nm in the absorption spectra of surface functionalized polyaniline nanofibers (SF-PNFs) can be explained on the basis of the dynamic block co-polymeric structure of polyaniline (PAni). Study of optical properties shows that surface functionalization of polyaniline nanofibers (PNFs) brings about a partial transition of emeraldine base (EB) into emeraldine salt (ES) form of polyaniline. This is confirmed from the FTIR analysis, which depicts rearrangement in the polyaniline chain due to oxidation at the amine sites of benzenoid rings and reduction at the imine sites of quinoid rings after functionalization with glutaraldehyde due to its higher reactivity towards amine group. The possible mechanisms of functionalization of polyaniline nanofibers depending on different chemical structures of glutaraldehyde under acidic condition have been discussed in detail.

<i>In Situ</i> Deposition of Conducting Polymer onto Pineapple Leaf Fiber

This paper reports the properties of newly developed electrically conductive natural fiber made up of pineapple leaf fiber (PALF) and conducting polyaniline (PANI). The results revealed that the in situ coating of PANI (1 wt.%) showed minimal reduction on the PALF tensile strength. Percolation concentration of the PANI was observed at 5 wt.% and its corresponding electron micrograph showed good polymer deposition with the characteristic globular PANI formation plus no fiber damages. This fiber material has potentials for many applications such as composites, electroactive fillers and conductive sheets.

The material combining conducting polymer and ionic liquid: Hydrogen bonding interactions between polyaniline and imidazolium salt

New type of interaction between polyaniline and ionic liquid leading to conducting polyaniline form is reported. Blue non-conducting polyaniline base was exposed to ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, and changed its colour to green. This was associated with the increase in conductivity by ten orders of magnitude from 6×10−11Scm−1 to 0.43Scm−1. The FTIR spectroscopic analysis suggests that (1) hydrogen bonding of hydrogen in imidazolium heterocycle with imine nitrogen in polyaniline combined with (2) hydrogen bonding of amine groups in polyaniline to oxygen atoms in trifluoromethanesulfonate anion are responsible for the observed effects. The quantum-chemical calculations of the corresponding hydrogen bonding interactions support this concept. The thermogravimetric analysis demonstrates improved thermal stability of the material compared with a standard polyaniline hydrochloride.