Electrodeposition of polyaniline nanostructures: A lamellar structure (original) (raw)
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… of Nanoscience and …, 2009
Potentiodynamic electrochemical synthesis was used to controllably synthesize nanofibers (mean diameter 48 nm) and/or nanoparticles (mean diameter 88 nm) of polyaniline (PANI) on gold electrodes. The films were characterized by cyclic voltammetry (CV), field emission gun scanning electron microscopy (FEG-SEM) and atomic force microscopy (AFM). The type and dimensions of the nanostructures depend on deposition conditions such as monomer concentration and scan rate. This study shows that the nucleation and growth steps play a key role on the film development and its nano-morphology.
Electrochemical Synthesis of Polyaniline Nanoparticles and Nanofibers
2006
The electrochemical deposition of polyaniline nanofibers and nanoparticles have been investigated on gold electrodes by cyclic voltammetry and their morphology by high resolution scanning electron microscopy and atomic force microscopy. The type and dimensions of the nanostructures obtained depend on deposition conditions such as monomer concentration, scan rate and electrical potential. We have observed that the nucleation and growth steps play a key role on the film growth and its nano-morphology.
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.
Polyaniline nanostructures and the role of aniline oligomers in their formation
Progress in Polymer Science, 2010
Polyaniline (PANI) is prepared by the oxidation of aniline. Depending on the acidity conditions during the chemical oxidation, different types of products can be identified. The aniline dimers, semidines, are the first oxidation products. In the next step, aniline trimers containing a phenazine moiety, the nucleates, are produced. At moderate acidity, pH > 3.5, the reaction pathway further leads to higher brown non-conducting aniline oligomers. Alternatively, when the acidity is sufficiently high, pH < 2.5, the nucleates convert to initiation centers that start the subsequent propagation of PANI chains. The model of phenazine nucleates is offered to explain the various supramolecular nanostructures produced by PANI. It is proposed that the hydrophobic nucleates randomly aggregate in the aqueous phase or become organized to form one-dimensional stacks stabilized byinteractions. This step is followed by the growth of PANI chains from the self-assembled nucleates. The evolution of the nanostructures is conveniently observed by the combination of microscopic and spectroscopic techniques. The random agglomeration of nucleates gives rise to PANI granules and regular self-assembly into stacks subsequently leads to PANI nanofibers. The growth of other nanostructures requires a starting template. A model of a flowing template combined with a helical nanotubular growth is proposed to account for the formation of nanotubes, monomer droplets serve as templates for microspheres. The detailed chemical structure of nucleates has still to be elucidated. The nucleates adsorb and self-assemble along various interfaces giving subsequently rise to additional conducting polymer morphologies. The adsorption of nucleates at solid surfaces immersed in the reaction mixture leads to PANI nanofilms or coatings of various substrates. The competition between nucleate adsorption and nucleate self-assembly may lead to more complex morphologies combining one-dimensional and three-dimensional features, such as nanobrushes, hairy spheres, etc. The control of nucleates self-assembly and of PANI growth, the involvement of various interfaces in this process, and the role of PANI conductivity are discussed. The nanostructures produced by other conducting polymers, especially by substituted PANI, polypyrrole, or poly(3,4-ethylenedioxythiophene) are also considered. Two potential extensions to the preparation of related materials, such as nitrogen-containing carbonized PANI nanostructures or the composites of conducting polymers with noble metals are outlined. The present review accounts for the latest development in the realm of PANI nanostructures in past few years and provides an upgrade in the models proposed for their formation.
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.
Formation of Polyaniline Nanofibers: A Morphological Study
Polyaniline (PANI) powders were prepared by solution precipitation, rapid mixing polymerization, and interfacial polymerization to find the key factors that influence the formation and growth of PANI nanofibers. In chemical oxidative polymerization of aniline, the morphology of the product is mainly determined by aniline concentration. In the case of lower aniline concentration, PANI nanofibers were formed and can be preserved and collected as final product, while in the case of higher aniline concentration, larger sized PANI particles or agglomerates were obtained owing to the growth of the nanofibers. Without participation of the oxidizing step, solid PANI samples with compact structures and dissimilar morphologies were achieved by random accumulation of PANI molecules. Figure 6. Schematic illustration of the formation of PANI with different morphologies. (If not stated, the reaction medium can be either mechanically stirred or ultrasonicated or left without any disturbance.) 1162 ).
Pulse electropolymerization and the characterization of polyaniline nanofibers
Electrochimica Acta, 2012
This work investigates the conditions required for the pulse galvanostatic electropolymerization of aniline in synthesizing polyaniline (PANI) nanofibers. In order to obtain uniform morphology in polyaniline nanofibers, the effects of such variables as pulse height (current amplitude), relaxation time (t off), pulse time (t on), bath temperature, HClO 4 and aniline concentrations were studied using SEM, TEM, FT-IR, UV-vis spectroscopy, cyclic voltammetry, TGA and DSC. The attained results reveal that the optimized conditions for the pulse height, t on , t off , aniline, HClO 4 , and solution temperature are 10 mA cm −2 , 0.5 s, 0.25 s, 0.1 M, 1 M, and 45 • C respectively. The synthesized polyaniline in the optimum conditions possess uniform nanofibers, with an average diameter of 80 nm and an average length of 4 m; further, it displays satisfactory electrochemical reversible redox reactions and high thermal stability.
Materials Letters, 2008
We present a new post-synthetic method for producing different nano-structures of Polyaniline (PANI), especially nano-fibers and nanoparticles of varying doping (oxidation) states, by simultaneous doping and electro-deposition from electrolyte solutions of undoped PANI (Emeraldine bases) and p-toluenesulphonic acid using constant applied voltage and varying deposition time. High Resolution Transmission Electron Microscopy analysis reveals that during the initial doping-dominated stage continuous connected conductive PANI Emeraldine salt nanofibers of diameter less than 50 nm are formed while in the later deposition-dominated stage, 30-50 nm sized isolated dispersed nano-particles of non conductive Leuco-Emeraldine are formed.
Controlled Electrochemical Polymerization Strategies for Electroactive Polyaniline Thin Films
Macromolecular Symposia, 2016
Polyaniline (PANI) thin films were successfully deposited using controlled electrodeposition (ED) technique from a mixed solution of 0.1M aniline and 0.5M H 2 SO 4 on ITO coated substrate. The effect of different deposition cycles 10, 25, 50, 75, 100 on thickness, optical and morphological properties of electrodeposited PANI thin films was studied. The formation mechanism of highly conducting form of polyaniline i.e. Emeraldine salt is explained. The support of Fourier transform-infra red (FT-IR) and Raman spectroscopy was given to confirm Emeraldine salt of PANI. Further DC electrical conductivity of PANI has been measured in temperature range from 300 to 500 K using two point probe method. The optical and morphological properties of PANI give its application towards flexible electrochromic glasses.