The effect of membrane equilibrium on the behaviour of electrochemically active polymers

The establishment and effects of the Donnan potential, ED, at the polymer/external solution interface in Electrochemically Active Macromolecular films, for the particular case of Polyaniline (Pani) is considered both from the fundamental and experimental viewpoints. In particular, it is demonstrated that ED should be considered together with the osmotic equilibrium and only under special circumstances, i.e. the osmotic pressure is negligible, ED may be calculated with the classical expression that arises from considering the ionic equilibrium alone. Also, it is demonstrated that, in Pani, the amount of protonated fixed sites depends on the external pH and the Donnan potential. The electrochemical response of the Pani film/aqueous solution system is studied as a function of the pH and the ionic strength. The parameter used in this work to evaluate the influence of ED in this kind of systems is the experimental peak potential, Ep,exp, which is the potential at the maximum current in the voltammetric response. Based on previous models, it is obtained an equation for the Ep,exp that allows to interpret the dependence of this parameter on the pH and the ionic strength.

[1]  G. Inzelt,et al.  An electrochemical quartz crystal microbalance study of the influence of pH and solution composition on the electrochemical behaviour of poly(aniline) films , 1993 .

[2]  Waldemar A. Marmisollé,et al.  The coupling among electron transfer, deformation, screening and binding in electrochemically active macromolecules. , 2010, Physical chemistry chemical physics : PCCP.

[3]  E. Grabner,et al.  Copper Hexacyanoferrate-Modified Glassy Carbon: A Novel Type of Potassium-Selective Electrode , 1985 .

[4]  G. Inzelt,et al.  Anion-involvement in electrochemical transformations of polyaniline. A radiotracer study , 1988 .

[5]  P. Flory.  Principles of polymer chemistry , 1953 .

[6]  Waldemar A. Marmisollé,et al.  Acid-base equilibrium in conducting polymers. The case of reduced polyaniline , 2014 .

[7]  M. I. Florit,et al.  Voltammetric study of the reduction and relaxation of poly(o-toluidine). Effect of the polymer thickness and the external electrolyte nature and concentration , 2000 .

[8]  N. Lakshminarayanaiah.  Equations of membrane biophysics , 1984 .

[9]  E. Geniès,et al.  La polyaniline: préparations, propriétés et applications , 1988 .

[10]  P. Ugo,et al.  Poly(2-vinylpyrazine) as a soluble polymeric ligand and as an electrode coating. Reactions with pentacyanoferrate(II) , 1989 .

[11]  L. Nyholm,et al.  A microelectrode study of the influence of pH and solution composition on the electrochemical behaviour of polyaniline films , 1991 .

[12]  Charles Tanford,et al.  Physical Chemistry of Macromolecules , 1961 .

[13]  M. C. Miras,et al.  Direct In Situ Evidence for Proton/Anion Exchange in Polyaniline Films by Means of Probe Beam Deflection , 1991 .

[14]  Waldemar A. Marmisollé,et al.  A formal representation of the anodic voltammetric response of polyaniline , 2011 .

[15]  M. I. Florit,et al.  The Redox Switching of Electroactive Polymers , 2004 .

[16]  K.F. Schoch,et al.  Conducting polymers , 1992, IEEE Spectrum.

[17]  A. Fitch.  Apparent formal potential shifts in ion exchange voltammetry , 1990 .

[18]  Wu-Song Huang,et al.  Polyaniline, a novel conducting polymer. Morphology and chemistry of its oxidation and reduction in aqueous electrolytes , 1986 .

[19]  D. Buttry,et al.  Determination of ion populations and solvent content as functions of redox state and pH in polyaniline , 1987 .

[20]  A. Bond,et al.  Principles of electrochemistry , 1987 .

[21]  E. Calvo,et al.  Donnan permselectivity in layer-by-layer self-assembled redox polyelectrolye thin films. , 2002, Journal of the American Chemical Society.

[22]  Su-Moon Park,et al.  Electrochemistry of Conductive Polymers III . Some Physical and Electrochemical Properties Observed from Electrochemically Grown Polyaniline , 1988 .

[23]  P. Kulesza,et al.  The membrane properties of Prussian Blue films on electrodes , 1989 .

[24]  Waldemar A. Marmisollé,et al.  Coupling between proton binding and redox potential in electrochemically active macromolecules. The example of Polyaniline , 2013 .

[25]  J. Redepenning,et al.  Influence of supporting electrolyte concentration and composition on formal potentials and entropies of redox couples incorporated in Nafion coatings on electrodes , 1986 .

[26]  M. Lapkowski,et al.  Spectroelectrochemical studies of proton exchange processes in the electrochemical reactions of polyaniline using pH indicators , 1990 .

[27]  G. Inzelt,et al.  Some problems connected with the study and evaluation of the effect of pH and electrolyte concentration on the behaviour of polyaniline film electrodes , 1990 .

[28]  G. Denuault,et al.  Scanning electrochemical microscope (SECM) study of the relationship between proton concentration and electronic charge as a function of ionic strength during the oxidation of polyaniline , 1994 .