Electroactive Polyaniline Films Research Articles

Characterization of In situ electrosynthesis of polyaniline on pencil graphite electrodes through electrochemical, spectroscopical and computational methods

This study investigates potentiodynamic synthesis of polyaniline (PANI) using pencil graphite electrodes (PGEs), aiming to elucidate deposition mechanisms under simple experimental conditions. By exploring PANI electrosynthesis through electrochemical, spectroscopic, and computational approaches, valuable insights into the physicochemical aspects of aniline polymerization are gained. The proposed synthetic method was challenged for the development of a new molecularly imprinted polymer for chloramphenicol on the surface of PGEs to obtain an innovative impedimetric sensor. The sensing platform shows a linear response in the target concentration range between 0.1 and 17.5 nM, in aqueous solutions, with a limit of detection of 0.03 nM and a limit of quantification of 0.09 nM. The results obtained suggest that the synthesis method proposed provide a way to obtain stable and electroactive polyaniline film with huge potential application.

Enzymatically synthesized polyaniline film deposition studied by simultaneous open circuit potential and electrochemical quartz crystal microbalance measurements

The chemical and enzymatic deposition of polyaniline (PANI) films by in situ polymerization was studied and the resulting films were characterized. The film formation and polymerization processes were simultaneously monitored by the evolution of the open circuit potential and quartz-crystal microbalance measurements. Different substrates, such as Indium-Tin oxide electrodes and gold-coated quartz-crystal electrodes were used as substrates for PANI deposition. Electroactive PANI films were successfully deposited by in situ enzymatic polymerization at low oxidation potential. The electrogravimetric response of the enzymatically deposited PANI film was studied by cyclic voltammetry in monomer-free acidic medium. The morphology of the films was observed by scanning electron microscopy, revealing a granular structure in enzymatically deposited PANI. The PANI films were also characterized by thermogravimetric analysis, electrochemical impedance spectroscopy, and X-ray photoelectron and Fourier-transformed infrared spectroscopy. The simultaneous use of quartz crystal microbalance and open circuit potential is presented as a very useful technique to monitor enzymatic reactions involving oxidoreductases.

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).

Reactive coupling of poly(ethylene glycol) on electroactive polyaniline films for reduction in protein adsorption and platelet adhesion

Poly(ethylene glycol) (PEG)-coupled polyaniline (PANI) film surfaces were prepared by incorporating the chlorine end-capped methoxy PEG (mPEGCl) of molecular weight of about 2000 onto the emeraldine (EM) base form of PANI via N-alkylation. The microstructure and composition of the mPEG-coupled PANI (mPEG-c-PANI) surfaces were characterized by atomic force microscopy, contact angle measurement and X-ray photoelectron spectroscopy. The concentration of surface-coupled mPEG increased with the increase in concentration of the mPEGCl solution. The mPEG-c-PANI film surfaces exhibited enhanced ability to repel protein adsorption, with only a moderate reduction in their electrical conductivity. The mPEG-c-PANI surface with a high concentration of coupled mPEG also exhibited good resistance towards platelet adhesion.

Electrochemical Characterization of Polyaniline in Nonaqueous Electrolyte and Its Evaluation as Electrode Material for Electrochemical Supercapacitors

In this study, the performance of a polyaniline (PANI) based supercapacitor where electroactive PANI films were prepared on carbon paper electrodes from a nonaqueous solution with an organic acid as the proton source was investigated. The use of nonaqueous media as electrolyte led to an increase of the electroactivity window from 0.75 V in aqueous media up to 1.0 V. Low frequency capacitance, evaluated by electrochemical impedance spectroscopy, of about 150 F/g is reported. Scanning electron microscopy indicated a highly porous material for deposited charges greater than 1 C/cm2. Constant current charge/discharge cycling of a symmetric supercapacitor based on PANI in nonaqueous medium was performed in a two-electrode cell configuration and a loss of about 60% of the discharge capacity was demonstrated after 1000 cycles. Tetramethylammonium methanesulfonate was also used instead of tetraethylammonium tetrafluoroborate as supporting electrolyte in acetonitrile for the charge/discharge testing of the PANI-PANI capacitor. Energy and power densities of approximately 3.5 Wh/kg and 1300 W/kg, respectively, were developed by this supercapacitor for a cell voltage of 1 V and a discharge time of 20 s. On the other hand, an asymmetrical supercapacitor with polypyrrole and polyaniline used as positive and negative electrodes, respectively, displayed slightly improved performance. Indeed, an energy density of 5 Wh/kg and a power density of 1200 W/kg were reported for discharge time of about 20 s with 1 M as electrolyte. © 2000 The Electrochemical Society. All rights reserved.

In situ X-ray photoelectron spectroscopy studies of interactions of evaporated metals with electroactive polyaniline films

X-ray photoelectron spectroscopy was employed for the in situ study of interactions between thermally evaporated Mg atoms and electroactive polyaniline (PANI) films of various intrinsic oxidation states. Quantitative changes in the N1s core-level spectra and the Mg2p core-level spectra, as well as the changes in surface chemical stoichiometry of these films throughout the Mg evaporation process were carefully monitored. Although the nitrogen sites appeared to be more attractive to the in-coming Mg atoms and the emeraldine base (EB) and nigraniline base (NA) films underwent an apparent decrease in intrinsic oxidation state ([=N-]/[-NH-] ratio) as a result of Mg evaporation, there is no direct interaction between the two species. On the other hand, the adsorbed oxygen from the bulk of the polymer film played a dominant role in the interfacial interactions between the polymer and the metal. Characterization of the delaminated indium-tin-oxide (ITO) and polymer surfaces from EB film and its camphorsulfonic acid-doped counterpart cast on ITO substrates had also been carried out to evaluate the interaction of PANI with the high work function metal.

Periodical oxidation current of single particle made of redox latex

A large electroactive particle, 1.3 μm in radius, is synthesized by coating the polystyrene latex with electroactive polyaniline film. It is monodispersed in size. Since the outside layer is electrically conductive, the electrode reaction propagates over the surface rapidly when it comes in contact locally with the electrode. Thus, it can be regarded as a model of a single redox particle, possessing the huge number of electrons, n. The colloidal suspension of the latex in HCl shows a steady-state anodic wave at a microelectrode. The value of n is 5.6×10 10 by means of bulk electrolysis. The limiting current after eliminating noise of the electric power source exhibits periodical oscillation with 14 Hz. No periodicity is found in the blank or in Fe(CN) 6 4− solution. The oscillation indicates collision of the particle to the electrode to cause the oxidation. The product of the current by the period is much smaller than the redox charge on the single particle.

QCM Analysis on Electropolymerization of Electroactive Polyaniline Film from Non-Aqueous Media

QCM Analysis on Electropolymerization of Electroactive Polyaniline Film from Non-Aqueous Media

Electroactive Polyaniline Film Deposited from Nonaqueous Media: III . Effect of Mixed Organic Solvent on Polyaniline Deposition and Its Battery Performance

Electroactive polyaniline (PAn) films were deposited from PC (propylene carbonate)‐EC (ethylene carbonate) and PC‐DME (1,2‐dimethoxyethane) mixed polymerization solutions containing aniline, , and . Higher dielectric constant solvents are necessary to deposit the PAn film where protons, dissociated from the acid, initiate the polymerization of aniline. Various PAn films deposited in the PC, the PC‐EC (50 mole percent), and the PC‐DME (50 volume percent) solutions were used for the cathode materials of the rechargeable lithium batteries. Charge capacity and discharge ability of the Li/PAn batteries in the electrolyte solution are almost the same, regardless of the polymerization solvents, such as and . The mixed solvent electrolyte solution effect on the Li/PAn (polymerized in the PC solution) batteries becomes much larger such as . Moreover, the electrochemical kinetic factors of the PAn films deposited in the various mixed polymerization solutions and also in the different electrolytes were experimentally determined by measuring the ac impedance. The results of the ac impedance analysis of each PAn film correlate well with the battery performances of Li/PAn cells.

Electroactive Polyaniline Film from Proton Free Nonaqueous Solution

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Electroactive Polyaniline Film Deposited from Nonaqueous Organic Media: II . Effect of Acid Concentration in Solution

Polyaniline films electrodeposited from acidified nonaqueous organic media were investigated for their electropolymerization behavior and charge‐discharge characteristics. The solution system used for the electropolymerization of polyaniline film was acidified propylene carbonate, which was previously found to be the best system for the preparation of a highly electroactive conducting polymer film. Electroactive polyaniline films only form in solutions where the mole ratio of acid to aniline monomer is greater than one. As the acidity is increased, the resultant polyaniline film exhibits greater electroactivity and better charge‐discharge performance of Li/polyaniline cathode cell. This effect may be ascribed to the high current efficiency in electro‐oxidative polymerization and high redox reversibility of PAn films prepared in the high acid content solutions.

Enzymatic synthesis of polyaniline film using a copper-containing oxidoreductase: bilirubin oxidase

Electroactive polyaniline films have been synthesized by using a copper-containing oxidoreductase, bilirubin oxidase (BOD). Enzymatic polymerization took place on the surface of BOD-adsorbed solid matrix which was in contact with a buffer solution containing aniline. Optimum conditions for enzymatic polymerization of aniline were investigated. Elemental analysis and IR spectroscopy indicated that the enzymatically synthesized film was polyaniline. The cyclic voltammetric studies demonstrated that the polyaniline film was electrochemically reversible in the redox properties in acidic aqueous solutions. Since the film retained enzymatic activity of BOD which was employed as a catalyst for polymerization, enzymatic polymerization seems promising in preparation of immobilized enzyme membranes.

Electrooxidation of aromatics to polymer films

AbstractThis report describes the electrochemical preparation and properties of polyaniline films prepared on a bare platinum electrode and on electrodes precoated with a thin film of inert polymer. Films were prepared and studied in several aqueous acid electrolytes including sulfuric, hydrochloric, nitric, trifluoromethylsulfonic, hydrofluoric and trifluoroacetic acid. It is observed that both the concentration and nature of the acid influence the kinetics of the switching reaction. In the more acidic solutions, the reaction has at dependence and depends on the movement of a front across the thickness of the film. In the less acidic solutions, the reaction has a t1/2 dependence and depends on the diffusion of ions in the film. The same response is observed for the oxidation and the reduction reaction. Polyaniline is also electroactive in other various nonaqueous solvents, such as, alcohols, acetic acid and acetonitrile, and voltammograms with well defined waves result when solution contains both organic salt and protic acid. Polyaniline was also prepared on a platinum electrode coated with an inert polymer film such as polymethylmethacrylate (PMMA). The resulting polymer blend is electroactive and the switching reaction is slower than for polyaniline formed on a bare platinum electrode. Finally, a brief description is given of electroactive polyaniline films which can be prepared by polymerization of aniline in a glow discharge.

Electroactive polyaniline films

Electroactive polyaniline films

Electroactive polyaniline films

Electroactive polyaniline films