Effect of anions on the electrosynthesis, electroactivity and molecular structure of poly(o-methoxyaniline) (original) (raw)
Related papers
Electrochimica Acta, 2001
The influence of anions on the electrodeposition, properties and overoxidation of poly(o-methoxyaniline), (POMA), is investigated by means of an electrochemical quartz crystal microbalance (EQCM) in the presence of HCl and HClO 4 acids. The effect of anions during polymerisation is explained in terms of the interactions of anions with neutral or oxidised monomer and trapping of hydrated anions in the polymer films. The exchange of anions and the solvent molecules is studied for the doping/undoping process of POMA. The degradation of the polymer films is considered taking into account the presence of water molecules in the polymer films. Scanning electron microscopy (SEM) was used to detect the changes in polymer morphology caused by degradation.
Electrochimica Acta, 2005
The in situ atomic force microscopy and the electrochemical studies on electropolymerization of the o-methoxyaniline in the 0.0-0.8 V versus NHE range of the electrode potential are described. It is proved that in the 0.0-0.3 V versus NHE a redox process takes place, resulting in the formation of poly(o-methoxyaniline) in its reduced form, leucoemeraldine. The different morphologies are exhibited by poly(o-methoxyaniline) under different polymerization conditions. The microscopic results show that with the increase of the monomer concentration in the bulk of electrolyte solution the globular morphology, related to the coil like molecular structure, is replaced by the fibrilar one, related to the opened-up, more conductive extended coil structure. It is shown that oxidation of a leucoemeraldine state of polymer to its emeraldine state results in the change of the morphology from the chain like structure to the massive fibrilar like structure. The reduction of oxidized polymer results in its irreversible fragmentation.
Electrochemical response of poly(o-ethoxyaniline) films produced by different techniques
Electrochimica Acta, 1995
Poly(o-ethoxyanilines) (POEA) were synthesized electrochemically and chemically in aqueous acid media. POEA films were readily obtained during the electrochemical deposition on platinum electrodes, while the chemically synthesized material was processed in the form of films either by drop coating or by Langmuir-Blodgett (LB) deposition. The open circuit potential values measured during the chemical synthesis, as well as the color changes observed, are in close agreement with those of the electropolymerization indicating basically the same changes in oxidation states of the polymer structures. The electrochemical response of all films was investigated by cyclic voltammetry. Two redox processes were observed after stabilization in the electrolyte solution, which are associated with interconversion reactions involving different oxidation and protonation states. Ultra-thin LB films required the shortest time for stabilization. POEA films displayed electrochromism, with color changes from yellow to violet as a function of the potential.
Electrochemical formation and copper modification of poly-o-methoxyaniline
Thin Solid Films, 2005
The electrosynthesis of poly-o-methoxyaniline (POMA) is studied under potentiostatic, potentiodynamic and pulse potentiostatic conditions. The three types of POMA layers are compared with respect to their electrochemical behaviour, stability and surface morphology. Copper electrodeposition is comparatively studied in the three types of POMA at two different thicknesses. It is established that for thin (< 1 Am) POMA coatings copper deposition occurs in one and the same way in all layers, defects (e.g. large pores) being most probably the promoters for metal crystallization. In contrast, thick POMA layers synthesized by the three electrochemical procedures show marked difference with respect to the amount and location of the deposited copper species. D .bg (V. Tsakova). Thin Solid Films 493 (2005) 88 -95 www.elsevier.com/locate/tsf
Synthetic Metals, 2008
A method was developed for the determination of the protonation constants (K nH,L HnL ), the stoichiometric factor of the protonation reaction (n) and pH of the half-color transition point (pH 1/2 ) of three different types of electrochemically polymerized poly(aniline) (PANI) and poly(o-methylaniline) (PoMeANI) films. The protonation constants describe the reversible emeraldine base (EB) to emeraldine salt (ES) transition. The calculations of the constants were based on absorbance data obtained from UV-vis measurements of the polymer films equilibrated in pH buffer solutions between pH 2 and 12.
Journal of Electroanalytical Chemistry, 1996
Poly (o-methoxyaniline) was chemically prepared in the presence of hydrochloric, p-toluene-sulfonic, dodecyl-benzene-sulfonic or dodecyl-sulfuric acids. Films of this polymer were prepared by casting and electrochemical, electrochromic and photoelectrochemical properties were studied. Cyclic voltammetry experiments show well-defined redox waves when the pH of the electrolyte is 1.0. Poly(o-methoxyaniline) films present high optical contrast in the visible range, when the potential is changed from the fully reduced to the fully oxidized state, independently of the dopant acid. The film obtained from the polymer doped with p-toluene-sulfonic acid, however, presents the highest contrast. Photoelectrochemical experiments also showed that this material yields photocurrent when irradiated with monochromatic light (330nm), and that the sign of the photocurrent depends on its oxidation state.
Mobilities of charge carriers in poly( o-methylaniline) and poly( o-methoxyaniline
Electrochimica Acta, 2004
Mobilities of charge carriers in poly(o-methylaniline) (PMA) and poly(o-methoxyaniline) (PMOA) films are electrochemically determined over a range of oxidation stages of the polymer films. In the low oxidation region, mobilities of both the polymers are comparable to that of polyaniline (PANI). In the high oxidation region, however, mobility values systematically decrease in the order of PANI > PMA > PMOA, showing that the bulky groups present at the ortho position play a more important role in the high oxidation region. The low mobilities of charge carriers in the high oxidation region explain why PMA and PMOA are less conducting than PANI. ß
V.V. Abalyaeva, O.N. Efimov Institute of Problems of Chemical Physics, Russian Academy of Sciences 1 Acad. Semenov Ave., Chernogolovka, Moscow Region, 142432 Russian Federation e-mail: avva@icp.ac.ru doi: 10.15518/isjaee.2015.12.004 Referred 6 July 2015 Received in revised form 10 July 2015 Accepted 14 July 2015 The article discusses the features of electrochemical synthesis and behavior of polyaniline and polyaniline based composites doped by electroactive anions (EAA). It has been found that in some cases electroactive anion forms complex with the aniline molecule in electrolyte, which performs as initiator of polymerization. This provides acceleration of the initial stage of aniline electropolymerization. As a result, it becomes possible to prepare highquality corrosion resistant polyaniline coatings on non-noble metal electrodes. The composites based on polyaniline and nanocarbon materials (carbon nanotubes, graphene oxide) have been prepared, which are promising for use in supercapacitors. Using EAA we developed electrochemical sensors to hydrogen and total content of antioxidants in food. Keywords: polyaniline, electroactive anions, doping, electrochemical behavior, applications.
Polymer, 2008
Oxidative electropolymerization of aniline (Ani) in phosphoric acid (H 3 PO 4 ) on composite 2B pencil graphite was accomplished using selected inorganic salts as supporting electrolytes. These salts determined the degree of conductivity of polyaniline (PAni) formed. The conductivity was in the order of CaCl 2 > KCl > ZnCl 2 > ZnSO 4 > Ca 3 (PO 4 ) 2 . The three pairs of redox peaks in the voltammogram of PAni formed in the presence of 0.06 M Ca 3 (PO 4 ) 2 and 0.2 M ZnSO 4 have shifted 300 mV to the negative potential. The shifting of peaks is strongly influenced by type of anions' presence in the salts. However, the nature of the available cations had no significant effect. The negative shifts of redox peaks were exploited to facilitate the electrocopolymerization of Ani and ortho-phenylenediamine (oPD). The formation of the poly(Ani-co-oPD) was confirmed by the FTIR spectra.