PANI) And Polypyrrole Research Articles

Structural, electrical, and electromagnetic properties of cotton fabrics coated with polyaniline and polypyrrole

AbstractIn this study, the structural, electrical, and electromagnetic properties of cotton fabrics coated with polyaniline (PAni) and polypyrrole (PPy) were investigated and compared. For the aims, anilin and pyrrole were used as monomers, andin situpolymerization on cotton fabric by chemical oxidative polymerization was performed. After production, the structural properties of the fabrics were determined with Fourier transform infrared spectroscopy and X‐ray diffraction. In addition, ultraviolet (UV) permeability, tensile strength, colorfastness, and electrical and electromagnetic measurements of the fabric samples were carried out. The resistance values of the cotton fabrics coated with PAni and PPy were found to be 350 and 512 Ω, respectively. The average electromagnetic shielding efficiency and average absorption values of the cotton fabrics coated with PAni were determined to be 3.8 dB and 48%, respectively, and these values for the cotton fabrics coated with PPy were 6 dB and 50%, respectively. Consequently, a significant difference was not observed between the resistance values and electromagnetic parameters of the fabrics coated with PAni and PPy, although the intact textile characteristics of the fabric coated with PPy were protected and improved, whereas the characteristics of the fabric coated with PAni were inferior. Moreover, we first report that the fabrics coated with conductive polymers had excellent UV‐protection properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

NANOCOMPOSITE ELECTRODES CONSISTING OF 3DOM CARBON WITH BIMODAL POROUS STRUCTURE AND CONDUCTING POLYMERS FOR ELECTROCHEMICAL CAPACITORS

Three-dimensionally ordered macroporous (3DOM) carbon with mesoporous walls was prepared by the colloidal crystal templating method using polystyrene (PS) and silica particles. Colloidal crystals consisting of monodispersed PS sphere (204 nm diameter) and silica particles (4–6 nm) were carbonized in Ar , and the silica was removed by etching in HF, and then 3DOM carbon with bimodal pore structure was obtained. Conducting polymers of polyaniline (PAn) and polypyrrole (PPy) were electrochemically deposited on the internal surface of macropores in 3DOM carbons. The mesopores were not closed after the deposition of the polymers. The composites were utilized as electrodes for electrochemical capacitors. The specific capacitances of prepared carbon– PAn and carbon– PPy composites were found to be 237 and 152 F g-1, respectively. The incorporation of the conducting polymers dramatically increased the charge storage capacities of the 3DOM carbon electrodes.

Electroanalysis of some common pesticides using conducting polymer/multiwalled carbon nanotubes modified glassy carbon electrode

The cyclic voltammetric behaviour of three common pesticides such as isoproturon (ISO), voltage (VOL) and dicofol (DCF) was investigated at glassy carbon electrode (GCE), multiwalled carbon nanotubes modified GCE (MWCNTs/GCE), polyaniline (PANI) and polypyrrole (PPY) deposited MWCNT/GCE. The modified electrode film was characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The electroactive behaviour of the pesticides was realized from the cyclic voltammetric studies. The differential pulse voltammetric principle was used to analyze the above-mentioned pesticides using MWCNT/GCE, PANI/MWCNT/GCE and PPY/MWCNT/GCE. Effects of accumulation potential, accumulation time, Initial scan potential, amplitude and pulse width were examined for the optimization of stripping conditions. The PANI/MWCNT/GCE performed well among the three electrode systems and the determination range obtained was 0.01–100 mg L −1 for ISO, VOL and DCF respectively. The limit of detection (LOD) was 0.1 μg L −1 for ISO, 0.01 μg L −1 for VOL and 0.05 μg L −1 for DCF on PANI/MWCNT/GCE modified system. It is significant to note that the PANI/MWCNT/GCE modified system results in the lowest LOD in comparison with the earlier reports. Suitability of this method for the trace determination of pesticide in spiked samples was also realized.

Liquid/Liquid Interfacial Polymerization To Grow Single Crystalline Nanoneedles of Various Conducting Polymers

Single crystalline nanoneedles of polyaniline (PANI) and polypyrrole (PPY) were synthesized using an interfacial polymerization for the first time. The interfacial crystallization of conductive polymers at the liquid/liquid interface allowed PANI and PPY polymers to form single crystalline nanocrystals in a rice-like shape in the dimensions of 63 nm x 12 nm for PANI and 70 nm x 20 nm for PPY. Those crystalline nanoneedles displayed a fast conductance switching in the time scale of milliseconds. An important growth condition necessary to yield highly crystalline conductive polymers was the extended crystallization time at the liquid/liquid interfaces to increase the degree of crystallization. As compared to other interfacial polymerization methods, lower concentrations of monomer and oxidant solutions were employed to further extend the crystallization time. While other interfacial growth of conducting polymers yielded noncrystalline polymer fibers, our interfacial method produced single crystalline nanocrystals of conductive polymers. We recently reported the liquid/liquid interfacial synthesis of conducting PEDOT nanocrystals; however, this liquid/liquid interfacial method needs to be extended to other conductive polymer nanocrystal syntheses in order to demonstrate that our technique could be applied as the general fabrication procedure for the single crystalline conducting polymer growth. In this report, we showed that the liquid/liquid interfacial crystallization could yield PANI nanocrystals and PPY nanocrystals, other important conductive polymers, in addition to PEDOT nanocrystals. The resulting crystalline polymers have a fast conductance switching time between the insulating and conducting states on the order of milliseconds. This technique will be useful to synthesize conducting polymers via oxidative coupling processes in a single crystal state, which is extremely difficult to achieve by other synthetic methods.

Inhibition of corrosion of mild steel by homopolymer and bilayer coatings of polyaniline and polypyrrole

Homopolymers and bilayers of polyaniline (PAni) and polypyrrole (PPy) coatings have been electropolymerized on mild steel by potentiodynamic synthesis technique in aqueous oxalic acid solutions. Characterization of coatings was carried out by cyclic voltammetry. Corrosion behavior of the polymer coated mild steel electrodes was investigated using linear anodic potentiodynamic polarization, Tafel test and electrochemical impedance spectroscopy (EIS) techniques in various aqueous corrosive solutions. Corrosion test results clearly showed that PPy and PAni/PPy bilayer coatings served as a stable host matrix on mild steel against corrosion. However, bilayers of PAni and PPy did not exhibit good combined properties of each polymer, unlike expected. PPy exhibited the best corrosion resistance among all coatings.

Polyaniline and polypyrrole modified conductive nanocomposites of polyfuran and polythiophene with montmorillonite clay

Nanocomposites of polyfuran (PF) and polythiophene (PTP) with montmorillonite clay (MMT) were prepared and modified by loading of polyaniline (PANI) and polypyrrole (PPY) moieties via polymerization of aniline (ANI) and pyrrole (PY) in aqueous dispersions of PF-MMT and PTP-MMT nanocomposites. Formation of PANI and PPY and their subsequent incorporation in the PF-MMT and PTP-MMT composites was confirmed by FTIR absorption studies. X-ray diffraction (XRD) patterns of PANI and PPY modified PF-MMT and PTP-MMT composites showed that PF-MMT and PTP-MMT intercalates were still present in the modified composites. Scanning electron microscopic analysis revealed distinctive morphological patterns of the various composite particles. The dc conductivity values of PANI and PPY modified PF-MMT and PTP-MMT composites were in the order of 10−2 S/cm in either system – a value much improved compared to the same for both of the unmodified PF-MMT (10−7 S/cm) and PTP-MMT (10−5 S/cm) nanocomposites respectively.

Relevance of polymer– and biopolymer–clay nanocomposites in electrochemical and electroanalytical applications

This paper introduces a general overview of polymer– and biopolymer–clay nanocomposites showing attractive properties for electrochemical and electroanalytical applications, including the latest advances achieved in this field by our research group. A part of the paper is devoted to introducing the many advances carried out since our pioneering work on PEO–smectite nanocomposites, including new approaches of synthesis and processing to improve the performance of these systems as solid electrolytes. Nanocomposites involving conducting polymers, e.g., polyaniline (PANI) and polypyrrole (PPy), as well as precursors of conducting materials, e.g., polyacrylonitrile (PAN), are currently tested as active phases of electrodes for different electrochemical devices. The combination of clays and biopolymers produces bio-nanocomposites that can be used as active phase of electrochemical sensors for the detection of ionic species.

Graphite/Polyaniline (GP) composites: Synthesis and characterization

Ever since the discovery of inherently conducting polymers (ICPs), research dealing with the applications of these unique materials continues to grow. The use of ICPs, especially polyaniline (PANi) and polypyrrole (PPy), and carbon black (CB) as conductive additives in the thermoplastics industry have been limited due to undesirable properties of each at high temperatures. Carbon black-ICP composites, however, have shown improved properties at higher temperatures. The applications of these composites are still limited because the conductivities are below that of carbon black alone and about the same order of magnitude as PANi. Graphite/ICP composites have also been touted as possible electrode materials in rechargeable batteries and have numerous other applications. The exploration of graphite/PANi composites in our research lab has yielded conducting composites which exhibit conductivities greater than the graphite or PANi alone. In addition to higher conductivities, these graphite/PANi composites exhibit controllable conductivities as a function of pH.

Intrinsically conducting polymers for electromagnetic interference shielding

AbstractThis paper summarizes and reviews the research on electromagnetic interference (EMI) shielding with intrinsically conducting polymers (ICPs), mainly polyaniline (PANI) and polypyrrole (PPY), and their composites in various frequency ranges. ICPs are new alternative candidates for EMI shielding applications due to their lightweight, corrosion resistance, ease of processing, and tunable conductivities as compared with typical metals. More importantly, the dominant shielding characteristic of absorption other than that of reflection for metals render ICPs more promising materials in applications requiring not only high EMI shielding effectiveness but also shielding by absorption, such as in stealth technology. Copyright © 2005 John Wiley & Sons, Ltd.

Determination of the specific capacitance of conducting polymer/nanotubes composite electrodes using different cell configurations

Composite materials containing 20 wt.% of multiwalled carbon nanotubes (MWNTs) and 80 wt.% of chemically formed conducting polymers (ECP) as polyaniline (PANI) and polypyrrole (PPy) have been prepared and used for supercapacitor electrodes. The well conducting properties of MWNTs and their available mesoporosity allow a good charge propagation in the composites. Moreover, due to the good resiliency of MWNTs, an excellent stability of the supercapacitor electrodes is observed. It has been shown that the capacitance values for the composites strongly depend on the cell construction. In the case of three electrode cells, extremely high values can be found from 250 to 1100 F/g, however in the two electrode cell much smaller specific capacitance values of 190 F/g for PPy/MWNTs and 360 F/g for PANI/MWNTs have been measured. It highlights the fact that only two-electrode cells allow a good estimation of materials performance in electrochemical capacitors. The applied voltage was found to be the key factor influencing the specific capacitance of nanocomposites. For operating each electrode in its optimal potential range, asymmetric capacitors have been built with PPy/MWNTs as negative and PANI/MWNTs as positive electrodes giving capacitance values of 320 F/g per electrode material.

Chemical and Biological Sensors Based on Electrochemical Detection Using Conducting Electroactive Polymers

The electrochemical behavior of composites of conducting electroactive polyaniline (PAn) and polypyrrole (PPy) formulated within cross-linked hydrogel networks was investigated by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Composite PAn gels displayed similar anodic charge density compared to the pristine conducting polymer (80 mC/cm2 and 84 mC/cm2, respectively), suggesting a similar degree of electroactivity between the two systems. Composite gels of PAn displayed fast cation transport with K+ diffusivity (Dappt= 5.31×10−7 cm2s−1) that were three orders of magnitude larger than that of pristine PAn (Dappt=3.12×10−10 cm2s−1), while PPy composite gels showed similar ferrocene anion diffusivity (Dappt=7.05×10−5 cm2s−1) compared to electropolymerized PPy (Dappt=6.54×10−5 cm2s−1). The electrochemical interactions between CYP2D6, a cytochrome P450 isoenzyme, and fluoxetine mediated by electroactive polyaniline films on glassy carbon electrodes (GCEs) were investigated. Cyclic voltammograms indicate that PAn is an effective mediator of CYP2D6 activity under anaerobic conditions. An analytical interrogation methodology based on small-amplitude, pulsed DC was developed and incorporated into the Electroconductive Polymer Sensor Interrogation System (EPSIS). Polypyrrole membranes were rendered biospecific by either copolymerization of pyrrole (Py) with 4-(1-pyrrolyl) butyric acid (4PyBA), followed by direct conjugation with 5-(biotinamido)pentyl amine (5BPA), or by reacting 4PyBA with 5BPA to form pyrrolyl-biotin conjugates. The biotinylated PPy was made responsive to glucose or urea by exploiting strong biotin-streptavidin binding to either streptavidin-glucose oxidase or biotin-urease conjugates. These bioactive conducting polymer membranes were demonstrated as conductimetric glucose and urea biosensing layers using the EPSIS. The rate of conductivity of the bioactive PPy membranes was observed to double upon increasing glucose concentration from 100 µM (4×10−6 S cm−1 s−1) to 600 µM (9×10−6 S cm−1 s−1).

Adsorbed surfactants as templates for the synthesis of morphologically controlled polyaniline and polypyrrole nanostructures on flat surfaces: from spheres to wires to flat films.

Nanostructures of polyaniline (PAni) and polypyrrole (PPy) with controlled morphologies have been synthesized on atomically flat surfaces using adsorbed surfactant molecules as templates. Atomic force microscopy (AFM) has been used to investigate polymer film formation on highly oriented pyrolytic graphite (HOPG) and chemically modified HOPG. Morphological control over the resulting polymer film is possible by the addition of coadsorbing molecules, manipulation of the length of the surfactant hydrophobe, or by changing the surface chemistry of the adsorbing substrate. Phase transitions between spheres, cylinders/wires, and featureless films have been observed which exactly parallel transitions between spheres, cylinders, and flat layers in the adsorbed surfactant. Parallel arrays of PAni nanowires can be synthesized with alignment evident over large areas in a simple self-assembly technique in which fabrication and arrangement take place simultaneously. Such a technique in which one can engineer sub-100-nm-ordered nanoscale pi-conjugated polymer structures of a desired shape by a simple self-assembly process presents potential as templates, sensors, and microelectronic devices.

Ionic transport in conducting polymers/nickel tetrasulfonated phthalocyanine modified electrodes

This work describes the study of the ionic transport in polyaniline (PANI) and polypyrrole (PPY) modified electrodes polymerized in presence of nickel tetrasulfonated phthalocyanine (NiTsPc). Elemental analysis and infrared spectroscopy were used to characterize the resulting composite films. The impact of the phthalocyanine incorporation was evaluated by electrochemical quartz crystal microbalance under potentiodynamic conditions. Results have shown that the presence of the negative charge (SO 3 − groups) modifies the nature of the ‘ionic exchange’ membranes, during the cycling. In the case of PANI/NiTsPc modified electrodes, the electroneutralization is mainly achieved by the participation of protons both in HCl and in camphorsulfonic acid (HCSA) electrolyte solutions. For PPY/NiTsPc composites, the cation contribution is dominant in the case of LiCl and NaCl solutions and the anion transport becomes important when CsCl and BaCl 2 solutions are used.

Device to Study Electrochemistry of Iron at a Defect of Protective Coating of Electronic Conducting Polymer

Protective effectiveness of electronic conducting polymers such as polyaniline and polypyrrole (PPy) are attributed to their high oxidation-reduction potential that allows maintaining the passive state of the substrate metal. However, when the polymer layer is damaged by a scratch or a hole, the protective actions of the conducting polymer remain unclear. For certain authors, the substrate metal becomes passive and for others it remains active. Therefore, it is important to know the electrode potential at the defect hole and the current coupling the polymer film and the damaged area. To determine them experimentally, a disk-in-ring electrode configuration was devised with a bare iron disk of 0.25 mm diam and a PPy coated large ring (5 mm o.d. and 0.4 mm i.d.). When the disk and the ring electrodes were connected, in 0.1 M K 2 SO 4 acidified at pH 4, the iron disk received a charge of 30 mC cm - 2 and became passive. After that, the coupling current increased progressively, and when one-quarter of the charge initially present in the PPy coating was consumed, the iron electrode became active. During these periods, the disk and the ring electrode potential were identical. The loss of protective effectiveness of PPy appeared, therefore, to be due, not to the charge exhaustion, but presumably to the increase of the internal electrical resistance of PPy film.

Electrochemical synthesis and characterization of conducting polymers in supercritical carbon dioxide.

This contribution reports the first synthesis of conducting polymers (CPs), specifically, polyaniline (PAn) and polypyrrole (PPy), in supercritical carbon dioxide (scCO2). CPs synthesized electrochemically in scCO2 were characterized with cyclic voltammetry (CV), four-point probe conductivity, scanning electron microscopy (SEM), and UV-vis spectroscopy. Preliminary data indicate that CPs synthesized by this method exhibit novel morphology and high conductivity comparable to that synthesized by traditional methods.

Application of Emulsion Intercalated Conducting Polymer-Clay Nanocomposite

Nanocomposites of conducting polymers (polyaniline (PANI) and polypyrrole (PPy)) with inorganic Na + -montnorillonite (MMT) clay were synthesized using dodecylbenzenesulfonic acid (DBSA) as both a dopant and an emulsifier. These nanocomposites were then adapted as both electrical conducting and electrorheological (ER) materials. The yield stress and current density of these ER fluids were found to increase with electrical field strength. The electrical properties and molecular structure of these nanocomposites were also investigated.

Electrical properties of polyaniline and polypyrrole bilayer structures

We have studied the electrical properties for conductive polyaniline (PANI) and polypyrrole (PPy). Also, bilayer structures consisted of electrochemically deposited PPy and PANI films onto PPy and PANI substrates prepared by chemical oxidative polymerization were investigated. In order to obtain structures with a high stability of electrical properties, the dopants compatibility with the polymers was studied. Special attention is given to I-V characteristics of the structures. On the basis of the experimental results, the electrical properties of bilayer structures based on PPy and PANI combined by different ways are described. In addition, the adhesive properties of different adherent layers, one to another, are discussed.

Electroactive polymer–SiO2 nanocomposites for metal uptake

The use of electroactive polymer–SiO2 nanocomposites for the uptake of gold and palladium from AuCl3 and PdCl2 in acid solutions respectively was investigated. The electroactive polymers used were polyaniline (PAN) and polypyrrole (PPY). The change in the physicochemical properties of the nanocomposites with metal uptake were of particular interest. In the case of gold uptake, the reaction rate increases with temperature from 0 to 60°C. The accumulation of elemental gold on the nanocomposites increases the diameter and decreases the surface area. The surface Au/N ratio as determined using X-ray photoelectron spectroscopy (XPS) is highly dependent on the rate of reactions even for the same amount of gold uptake. The uptake of palladium from PdCl2 is much more difficult to accomplish. High rates of uptake can only be achieved with the electroactive polymers reduced to their lowest oxidation state and unlike the case of gold uptake, the palladium on the microparticles does not exist in the elemental form but as a Pd(II) compound.

Enhancement of Growth and Adhesion of Electroactive Polymer Coatings on Polyolefin Substrates

The coating of polyaniline (PAN) and polypyrrole (PPY) films on low-density polyethylene (LDPE) substrates was carried out via immersion of the substrate in a reaction mixture of the monomer, an oxidizing agent, and a doping agent or counterion. The effects of the immersion time in the reaction mixture, the doping agent, and the nature of the substrate's surface were investigated. The coatings were characterized using ultraviolet (UV)−visible absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and conductivity measurements. The substrate's surface plays a major role in determining the growth and adhesion of the electroactive film. LDPE grafted with acrylic acid (AAc) greatly enhances the growth of the electroactive films on the substrate surface. The N,N-dimethylacrylamide (DMAA) graft copolymerized LDPE also affects the growth of the PAN film but not that of the PPY film. Both the AAc and DMAA graft copolymerized substrates promote the adhesion of the electroactive films.

Polythiophene, polyaniline and polypyrrole electrodes modified by electrodeposition of Pt and Pt+Pb for formic acid electrooxidation

The electrosynthesis of polythiophene (PTh), polyaniline (PANI) and polypyrrole (PPy) films modified by dispersion of Pt or Pt+Pb and its employment in the electrocatalytic oxidation of HCOOH are studied and compared. The influence of parameters such as polymer film thickness, the number of dispersed Pt particles, the amount of Pb deposited and the presence of Pb2+ in the electrolyte on the electrooxidation of HCOOH is investigated. Electrode systems including the polymer and a mixture of Pt and Pb particles show a better electrocatalytic activity than electrodes having a polymer–Pt combination or bulk Pt electrodes. Furthermore, during the electrooxidation of HCOOH using polymer–(Pt+Pb) electrodes the presence of fewer poisoning species is observed, indicating that the role of Pb in these electrode systems is in agreement with the Pb adatom effect observed when bulk Pt electrodes are used. However, the presence of Pb(ii) in the electrolyte is not required for the PTh–(Pt+Pb) electrode system and, in addition, a better electrocatalytic effect is obtained in this case. With application of an appropriate E/t program the activity is unchanged over a long time.