Electrochemical and chemical synthesis of polyaniline on the surface of vacuum deposited polyaniline films (original) (raw)
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Electroless deposition of polyaniline: synthesis and characterization
Surface and Interface Analysis, 2008
Polyaniline (PANi), as conductive polymer, constitutes an attractive material for electronic and optical applications. Different from electropolymerization and chemical oxidative polymerization, electroless deposition is another method for synthesizing PANi. Aniline can polymerize slowly and spontaneously on platinum or palladium surface in an aqueous acid solution of the monomer. This reaction proceeds via an electrochemical mechanism that involves the reduction of dissolved oxygen as cathodic and oxidation of aniline as anodic half-reactions at the metal/solution interface. PANi, obtained by electroless synthesis, was compared to chemical oxidative and electropolymerized ones by XPS and SEM. The product of electroless deposition is found to be chemically similar to the others but its morphology is different. The PANi film growth and morphology are studied as a function of time and temperature.
Effect of temperature on the electrochemical synthesis and properties of polyaniline films
Journal of Non-Crystalline Solids, 2010
The effect of temperature on the electrochemical oxidative polymerization of aniline and on the electrochemical properties of the resulting polyaniline (PANI) film was studied. The electrochemical deposition of PANI has been carried out on platinum at different temperatures. Three different films (PANI-25, PANI-40 and PANI-60) have been prepared at 25, 40 and 60°C by electrochemical polymerization and characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Increasing the synthesis temperature leads to an increase of the polyaniline films thickness from 0.4 to 0.9 lm and, respectively, 1.1 lm, associated with an increase of the films capacitances from 3 Â 10 À2 F cm À2 to 7 Â 10 À2 F cm À2 and 10 Â 10 À2 F cm À2 . The impedance measurements showed that only PANI-25 and PANI-40 exist in the conductive state over a large potential window, while PANI-60 has an intermediate behavior at low and high electrode potentials.
2018
Polyaniline membranes of aniline were produced using an electrochemical method in a cell consisting of two poles. The effect of the vaccination was observed on the color of membranes of polyaniline, where analysis as of blue to olive green paints. The sanction of PANI was done by FT-IR and Raman techniques. The crystallinity of the models was studied by X-ray diffraction technique. The different electronic transitions of the PANI were determined by UV-VIS spectroscopy. The electrical conductivity of the manufactured samples was measured by using the four-probe technique at room temperature. Morphological studies have been determined by Atomic force microscopy (AFM). The structural studies have been measured by (SEM).
Thin polyaniline (PAN) ®lms were prepared by evaporation of emeraldine base in vacuum at 275±3258C, followed by deposition of the vapors onto SnO 2 ±glass transparent electrodes. With the purpose to restore the original structure of the polymer, the films were subjected to a postdeposition oxidative treatment in HNO 3 according to the following three different procedures: (1) treatment in vapors of 10 M acid, (2) treatment in 2 M HNO 3 aqueous solution, (3) cyclic treatment: in 2 M aqueous HNO 3 , then in 2 M aqueous NH 3 and so on. Electrochemical and spectroelectrochemical characteristics, namely cyclic voltammetry curves at different sweep rates and optical spectra at stationary potentials, were investigated for these films. It was found that the above characteristics of the films oxidized according to the cyclic procedure are most close to those of conventional PAN. However, in the optical spectra recorded at 0.0 V (vs. Ag/AgCl) for all the vacuum deposited films no absorption band in the area longer than 800 nm was observed. The results are discussed in terms of correlation of changes in the spectroelectrochemical characteristics with formation of heterogeneous structure of PAN by means of arising of intermolecular interactions, as well as, with specific features of vacuum the deposited PAN films. #
Modification And Designing Of Electrodeposited Polyaniline Films For Potential Applications
AIP Conference Proceedings, 2011
The electrodeposited polypyrrole (PPY) film over ITO coated glass substrate has been prepared and its current voltage response using Schottky emission theory has been analyzed. The electrodeposition of PPY has ben carried out by electrochemical polymerization of 0.2 M pyrrole monomer and cycling the potential between-0.2V to 0.8 V at a scan rate of 20mV/s using KCl as supporting electrolyte. The formation of polymer has been confirmed by X-ray diffraction and FTIR measurements whereas the surface morphology has been observed using scanning electron microscope. The band gap of PPY film has been calculated using UV visible spectroscopy and found to be 2.4 eV. In addition, the current-voltage response of deposited film was also recorded to evaluate its electronic attributes such as barrier height (Ø B) and constant factor (ȕ). The results revealed the Ø B and ȕ values of 0.314 eV and 1.72×10-4 , respectively. These films may have potential applications in electronic and optoelectronic sensing devices.
Polyaniline Thin Film Prepared by Electrochemical Polymerization Method
Biointerface Research in Applied Chemistry, 2021
Polyaniline (PANI) slim film was set up by electrochemical polymerization strategy at room temperature in a standard three-electrode cell from (0.1M) aniline monomer and (0,5M) from Sulfuric acid in the presence of distilled water. The development of PANI film was portrayed by Voltammetric studies, SEM, XRD, and FTIR. Voltammetric studies were performed in 0.5 M acidic aqueous solutions using H2SO4. The XRD design demonstrated that the diffraction top at 2θ = (30˚). The FTIR spectroscopy spectra give particular and unmistakable bonds at 3500, 1572.52, 1302.53, 831.98, and 592.85 cm-1.
Comparison of Chemically and Electrochemically Prepared Polyaniline. Films. 1. Electrical Properties
Chemistry of Materials, 1995
Relaxation phenomena in thin polyaniline films synthesized chemically and electrochemically are investigated by UV-vis and IR spectroscopy. It is shown that the relaxation process carried out from the electrochemically oxidized or electrochemically reduced states of the polyaniline always proceeds toward the emeraldine state. The relaxation process in acid is governed by disproportionation and formation of semiquinone radicals. The changes in the population density of the polaronic states within the polaronic band allows determination of the change in the oxidation state and consequently the change in the position of the Fermi energy level. The formation of polaronic states is ascertained by diffusion of ions from or into t h e polyaniline matrix in solution and
A spectroelectrochemical study of thin electrochromic polyaniline (PAN) films deposited on SnO, glass substrates by a vacuum thermal evaporation method has been carried out. The films obtained were studied by means of spectral, spectroelectrochemical and electrochemical methods, and the results were compared with those obtained for PAN films prepared by electrochemical polymerization. Spectroelectrochemical data (obtained under a potential step) and cyclic voltammetry data showed that the evaporated PAN films did not undergo a second oxidation stage resulting in formation of a quinoid structure. Current vs. time dependences processed according to the Cottrell equation showed that the diffusion coefficient for the evaporated PAN layers was almost a factor of 3 lower than that for the electrochemically deposited films. During cyclic tests in a real electrochromic optical filter the evaporated PAN layers exhibited a stability more than 2.5 times higher than that of the electrochemically deposited films.
Novel approach to the synthesis of polyaniline possessing electroactivity at neutral pH
Synthetic Metals, 2019
A new approach is proposed for the synthesis of polyaniline via electrochemical polymerization of aniline at a very low concentration on a modified electrode surface. The electrode was modified with a sulfonated polyaniline, poly(2-methoxy aniline-5-sulfonic acid) (PMAS), which acted as an electroactive conductive template for the aniline monomer. The electrode surface was modified with PMAS via a number of different methods including cyclic voltammetric and potentiostatic deposition as well as dip and drop casting water-soluble PMAS onto the electrode surface. Electrochemical polymerization of aniline was then carried out at the surface of the modified electrode. Effect of different variables such as PMAS concentration, volume and pretreatment of the modified electrode on the polymerization of aniline was studied. The polymer synthesized at the PMAS modified electrode was characterized by electrochemical and UV-vis spectrophotometic techniques. Electrochemical studies showed that even at very low concentration of aniline (5.0 mM), an adherent, uniform and stable polyaniline film was deposited on the electrode surface. Without any further treatment, this polyaniline layer was found to be electroactive at a neutral pH which is crucial for biosensing applications.
A comparative voltabsorptometric study of polyaniline films prepared by different methods
A comparative cyclic voltabsorptometric study was carried out for polyaniline (PAn) films prepared by electro-chemical polymerization and vacuum thermal evaporation. The absorption values were measured at different characteristic wavelengths (895, 755, 665, 435, and 325 nm) corresponding to the individual absorption bands separated by us earlier from the spectra using the Alentsev-Fock method. Differential voltabsorptometric curves (dA/dt vs. potential (DCVA)) measured in aqueous HCl were compared with ordinary cyclic voltammetry (CVA). The experiments for different sweep rates were also compared. It was found that the DCVA peak at 895 nm corresponds perfectly to the CVA peak both in the electrosynthesized and the vacuum deposited PAn. The DCVA peak at 435 nm (cation-radicals) precedes the CVA peak (similar to the maximum of the EPR signal), while that at 755 nm (polarons or cation-radical dimers) lags behind the CVA peak. For the vacuum deposited films an intense intermediate DCVA and current peaks (at about 0.6 V vs. Ag/AgCl) are observed. The results are discussed in terms of the heterogeneous structure of PAn; particularly, its specific features in the films prepared using different methods.