Polypyrrole film coated electrode

Tezuka, Y, Kimura, T., Ishii, T., and Aoki, K., Concentration distribution of conducting species with time-resolution in electrochemical undoping process at the polypyrrole film coated electrode in the light of electric percolation, J. Electroanal. Chem., 395, 51-55 (1995). 

Polymerization solutions were 0.5 M in pyrrole and 0.2 M in Et4NBF4. Pyrrole was polymerized (and deposited) galvanostatically a current density of 1.0 mA cm" was employed. Reproducible steady state potentials of 0.84 V + 0.01 V were observed during film deposition at this current density. After deposition, the polypyrrole film-coated electrode was transferred to monomer-free, 0.2 M Et4NBF4. All subsequent electrochemical measurements were performed in this electrolyte. 

Typical Nernst plot for polypyrrole film-coated electrode obtained from coulometric titration experiment. Film thickness - 0.27 fm. See text. 

Polypyrrole film-coated electrode at +0.4 V to -0.6 V peak to peak potential. 

Employment of a polypyrrole-coated microelectrode brought about the amplification of the electrochemical effect. By the adoption of a high frequency square wave potential application, the susceptibility of the target cell at the interface of the microelectrode to bursting was remarkably enhanced. It should be noted that the polypyrrole film-coated electrode demonstrated interesting functions even under the conditions needed for a bare platinum electrode. This might be interpreted by the electrochemically induced influx of dopant anions onto the polypyrrole film matrix, which seems to result in drastic pH changes in the localized area, i.e., the interface between an electrode and bulk solution. 

A molecularly imprinted polypyrrole film coating a quartz resonator of a QCM transducer was used for determination of sodium dodecyl sulphate (SDS) [147], Preparation of this film involved galvanostatic polymerization of pyrrole, in the presence of SDS, on the platinum-film-sputtered electrode of a quartz resonator. Typically, a 1-mA current was passed for 1 min through the solution, which was 0.1 mM in pyrrole, 1 mM in SDS and 0.1 M in the TRIS buffer (pH = 9.0). A carbon rod and the Pt-film electrode was used as the cathode and anode, respectively. The SDS template was then removed by rinsing the MlP-film coated Pt electrode with water. The chemosensor response was measured in a differential flow mode, at a flow rate of 1.2 mL min-1, with the TRIS buffer (pH = 9.0) as the reference solution. This response was affected by electropolymerization parameters, such as solution pH, electropolymerization time and monomer concentration. Apparently, electropolymerization of pyrrole at pH = 9.0 resulted in an MIP film featuring high sensitivity of 283.78 Hz per log(conc.) and a very wide linear concentration range of 10 pM to 0.1 mM SDS. 

An interesting composite material has been prepared by the electropolymerization of pyrrole on polyacetylene electrodes (45). Because oxidized polypyrrole is far more stable in air than polyacetylene, the resulting composite has the stability of polypyrrole. With different synthetic conditions, either a thin layer of polypyrrole was deposited over individual fibrils of the polyacetylene film or a dense polypyrrole film coated the entire film. When the dense polypyrrole film covered the entire polyacetylene film, the interior... 

V, A, Ch Study of V, A, and Ch behavior of AA at polypyrrole-dodecyl sulfate film-coated electrodes No data No data 5.0 Aqueous solutions 1994 175 ... 

Zhiqiang, G. 1994. Electrochemistry of ascorbic acid at polypyrrole/dodecyl sulphate film-coated electrodes and its application. J. Electroanal. Ghent. 365 197-205. 

Fig. 18.8. Doping and undoping of a poly(pyrrole) film during oxidation and reduction cycles. When a poly(pyrrole) coated electrode is cycled between the reduction and oxidation potentials, the current observed at the oxidation potential is related to the ability of anions to enter the polymer film and dope the polypyrrole.

Composites of polypyrrole and poly(vinyl chloride) have been prepared by several groups (64-67). Polythiophene-poly(vinyl chloride) composites have also been prepared (68). The electropolymerization of pyrrole on poly(vinyl chloride)-coated electrodes yielded composites with mechanical properties (tensile strength, percent elongation at break, percent elongation at yield) similar to poly(vinyl chloride) (65) but with a conductivity of 5-50 S/cm, which is only slightly inferior to polypyrrole (30-60 S/cm) prepared under similar conditions. In addition, the environmental stability was enhanced. Morphological studies (69) showed that the polypyrrole was not uniformly distributed in the film and had polypyrrole-rich layers next to the electrode. Similarly, poly(vinyl alcohol) (70) poly[(vinylidine chloride)-co-(trifluoroethylene)] (69) and brominated poly(vinyl carbazole) (71) have been used as the matrix polymers. The chemical polymerization of pyrrole in a poly(vinyl alcohol) matrix by ferric chloride and potassium ferricyanide also yielded conducting composites with conductivities of 10 S/cm (72-74). 

The presence of a derivatized surface layer can affect the energetics as well as the kinetics of electrode reactions. It has been found that the flatband potentials of -Si and p-Si electrodes coated with conducting polypyrrole films are shifted by 300 and 500 mV in CH3CN solution." The reaction kinetics on polymer derivatized surface can further be enhanced by impregnation of noble metals such as Pt particles into the... 

These conducting polymers are sometimes termed organic metals, and their formation as thin-film coatings on an electrode involves nucleation phenomena so perhaps by analogy with metal electrodeposition under ultrasound there have been studies to improve the quality of the deposited materials. Polypyrrole readily forms acceptable films under a wide variety of conditions [174], although there are subtle distinctions in behavior as a result of exact preparation procedure [175], Ultrasound from 38 or 500 kHz baths does not appear to appreciably improve polypyrrole film formation, at least from MeCN electrolyte at the normal current density of 1 mAmp... 

R. A. Bull, F.-R. F. Fan and A. J. Bard, Polymer films on electrodes VII. Electrochemical behavior at polypyrrole-coated platinum and tantalum electrodes, J. Electrochem. Soc. 129 (1982) 1009-1015. 

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