Polypyrrole electrochemical properties

Here we introduce a personal point of view about the interactions between conducting polymers and electrochemistry their synthesis, electrochemical properties, and electrochemical applications. Conducting polymers are new materials that were developed in the late 1970s as intrinsically electronic conductors at the molecular level. Ideal monodimensional chains of poly acetylene, polypyrrole, polythiophene, etc. can be seen in Fig. 1. One of the most fascinating aspects of these polymeric... 

This reverse electrochemical control of the gel composition and volume is the basis for the singular electrochemical properties and the concomitant applications of conducting polymers. Reactions and properties based on polypyrrole films can be summarized as shown in Table 5 and below ... 

Electronically conducting polymers (ECPs) such as polyaniline (PANI), polypyrrole (PPy) and po 1 y(3.4-cthy 1 cncdi oxyth iophcnc) (PEDOT) have been applied in supercapacitors, due to their excellent electrochemical properties and lower cost than other ECPs. We demonstrated that multi-walled carbon nanotubes (CNTs) prepared by catalytic decomposition of acetylene in a solid solution are very effective conductivity additives in composite materials based on ECPs. In this paper, we show that a successful application of ECPs in supercapacitor technologies could be possible only in an asymmetric configuration, i.e. with electrodes of different nature. 

J.L. Bredas, R. Silbey, D.S. Boudreaux, and R.R. Chance, Chain-length dependence of electronic and electrochemical properties of conjugated systems polyacetylene, polyphenylene, polythiophene, and polypyrrole, J. Am. Chem. Soc., 105 6555-6559, 1983. 

Table 1. Structures and electrochemical properties of polypyrroles and polythiophenes...

Fig. 11.8. Current density as a function of rotation rate during growth of electrodeposited polypyrrole film at 0.550 ( ), 0.600 ( ), 0.650 (T), and 0.700 ( ) V. (Reprinted with permission from D. J. Fermin, M. Mostany, and B. Scharifker, Electronically Conducting Polymers Synthesis and Electrochemical Properties of Polypyrrole, Curr. Topics Electrochem. 2 132-136, 1993.)...

CP sensors [17] exploit the electrochemical properties of compounds such as polypyrrole and polyindole. Films of the polymers are deposited on electrical conductor components. When analyte molecules are absorbed into the film the conductivity changes. The activity of CP films is fine-tuned by derivatizing the polymer with different functional groups thereby rendering the CP sensors... 

Various para substituted poly-N-arylpyrrole polymer films were prepared and their electrochemical properties were measured. Of particular interest are the poly-N-p-nitrophenylpyrrole films which can be oxidized to produce the polypyrrole cation and reduced to produce the nitrophenyl anion. The polymer films can be repeatedly switched between the neutral, cationic and anionic forms with coulombic reversibility and with little ir-interaction between the pyrrole and the aryl ring. 

The electrochemical properties of conductive polymer systems are important with regard to understanding the electrochemical doping process and in applications of conductive polymers as battery electrodes. We have developed a computational method, based on the Valence Effective Hamiltonian technique, which is remarkably effective in the computation of oxidation and reduction potentials of a variety of conjugated polymers (polyacetylene, polyphenylene, polythiophene, polypyrrole) and their oligomers. 

S. Kawabata, H. Yoneyama and H. Tamura, Redox behavior and electrochromic properties of polypyrrole films in aqueous solutions, Bull. Chem. Soc. Jpn., 1984, 57, 2247 P.C. Bookbinder and M.S. Wrighton, Electrochromic polymers covalently anchored to electrode surfaces. Optical and electrochemical properties of a viologen-based polymer./ Electrochem. Soc., 1983,130, 1080. 

Polypyrrole electrochemically polymerized within a matrix resin electrically conducting material with improved mechanical properties over those of PPy Lindsey Street, 1985... 

Ram et al. reported electrochemical properties of GOD assembled with a conductive polypyrrole through LbL techniques [191]. The results obtained provided information, with respect to the electron transfer processes, on the spatial arrangement of GOD molecules on the polypyrrole surfaces, which might give crucial and important insights for construction of glucose-responsive biosensors. Wollenberger... 

Y-W. Ju, J-H. Park, H-R. Jung, and W-J. Lee, Electrochemical properties of polypyrrole/ sulfonted SEBS composite nanofibers prepared by electrospinning, Electrochim. Acta, 52, 4841 847 (2007). 

Polypyrrole nanotubes synthesized at a constant potential using the pores of nanoporous polycarbonate (PC) particle track-etched membranes as a template [63,64] and polypyrrole nanowires synthesized at a constant potential of 0.9 V (vs. SCE) using nanochannels of proton-modified natural zeolite clinoptilolite [65] have been reported. Their electrochemical properties were improved compared to the conventional polypyrrole. 

J.Y. Kim, K.H. Kim, and K.B. Kim, Fabrication and electrochemical properties of carbon nanotube/polypyrrole composite film electrodes with controlled pore size, J. Power Sources, 176(1), 396 02 (2008). 

The unique transport characteristics of conducting polymer membranes that we have demonstrated arise from their electrochemical properties. For the purpose of this discussion polypyrroles will be used, however, similar principles apply to transport across polyaniline membranes. 

Novel conductive composite films have been developed by Kaplin and Qutubuddin [101] using a two-step process microemulsion polymerization to form a porous conductive coating on an electrode followed by electropolymerization of an electroactive monomer such as pyrrole. The porous matrix was prepared by polymerizing an SDS microemulsion containing two monomers, acrylamide and styrene [102], The electropolymerization of pyrrole was performed in an aqueous perchlorate or toluenesulfonate solution. The effects of polymerization potential on the electropolymerization, morphology, and electrochemical properties were reported [101]. The copolymer matrix improves the mechanical behavior of the polypyrrole composite film. 

Park HS, Kim YJ, Hong WH, Lee HK (2006) Physical and electrochemical properties of Nafion/polypyrrole composite membrane for DMFC. J Membr Sci 272 28-36... 

The most elegant approach to design polypyrrole, polyaniline or polythiophene-based porphyrin, phthalocyanine or Schiff base matrices involves the electrochemical polymerization of suitably designed substituted N4-macrocyclic monomers. We and others have shown that the electro-oxidative polymerization of such species (see significant examples in Figure 8.3) leads to the formation of films having the electrochemical properties of the monomeric complex" . ... 

For improving the energy storage efficiency, ECP/CNM nanocomposites are widely used in electrochemical energy storage devices. These include lithium-ion batteries and supercapacitors. Polyaniline/CNM nanocomposites and polypyrrole/CNM nanocomposites are the major composite nanostructures used for this piupose due to their superior electrochemical properties, low cost and easy processing methods. 

Lithium-ion batteries require novel materials for increasing their cychng stability and power delivering capability. Polypyrrole/reduced graphene oxide nanocomposite is used as cathode in a lithium-ion battery and enhanced electrochemical properties are observed such as high rate capability and improved cycling stability [71 ]. 

Supercapacitors require electrode materials that have good electrical conductivity, good electrochemical properties, high chemical and environmental stabilities, etc. Various ECP/CNM nanocomposites such as polyaniline/carbon nanofiber [31,32,34], polyaniline/graphene [62,67-69], and polypyrrole/graphene [73,75] are widely used as electrode materials in supercapacitors. 

Electronic noses The so-called electronic noses consist of chemical gas sensors that are able to monitor changes in the offgas composition of fermentation processes. The different sensors of electronic noses are based on conductive polymers (CP), metal oxide semiconductors (MOS), metal oxide semiconductor field effect transistors (MOSFET), or quartz crystal microbalance (QCM). CP-based sensors use the electrochemical properties of polymers like polypyrrole or polyindole. The absorbance of selected molecules of the off-gas into the polymer film causes changes in the sensors conductivity. MOS sensors possess an electrochemically active surface of metal oxides like tin oxide or copper oxide. The sensitivity... 

Polypyrrole can be synthesized by both electrochemical and chemical methods. Although the synthesis of polypyrrole has been described before, studies on the electrochemical properties of polypyrrole intensified after Diaz et al [32] reported high-quality polypyrrole film electrochemically obtained by improving Dall Olio s method. 

Polypyrrole can be synthesized by the galvanostatic or potentiostatic electrolysis of nonaqueous or aqueous solution containing pyrrole monomer and supporting electrolyte. Metals, such as Pt and Au, carbon, or semiconductors can be used as electrode materials. Pt is most often used for electrochemical measurements of polypyrrole film electrodes. The physical and electrochemical properties of synthesized polypyrrole are greatly influenced by the electrolysis current, potential conditions, electrode materials, concentrations of the pyrrole monomer and supporting electrolyte, electrolyte (dopant) and solvent materials, temperature, and so on. 

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