Polypyrrole PPy

A novel route to pure and composite fibers of polypyrrole was recently reported by Han and Shi [42]. An organic salt (FeAOT) was synthesized by the reaction of sodium l,4-bis(2-ethyUiexyl)sulfosuccinate (AOT) and ferric chloride. It was fabricated into nanofibers by manual drawing and electrospinning. Long PPy fibers were obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique was extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy-MWCNT fibers). The PPy and PPy-MWCNT fibers had a nanoporous morphology, a conductivity of 10-15 S cm and a tensile strength of 12—43 MPa. Studies of the electrochemistry and current-voltage characteristics of the PPy fibers were also reported. 

Alignment of nanostructures, providing the ordering at a large scale, is one of the key factors to obtain the high performance of functional nanomaterials. However, most resultant conducting polymer nanostructures synthesized at the current time 

They proposed that the formation of the oriented PPy nanofibers is related to the water oxidation that leads locally to the formation of O2 nanobubbles, which protect the PPy film against hydroxyl radicals (i.e., against overoxidation) allowing the electropolymerization of pyrrole to continue growing nanowires. 

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Figure 19. (1) Oxidized polypyrrole (PPy) film electrogenented on a steel electrode. (2) A tape was fastened to the dry polypyrrole film (A). B is doublesided tape and C is a protective sheet of paper. (3) The bilayer device with a protective film is removed from the electrode. (4) The protective sheet is peeled off and the bilayer is ready to work. (Reprinted from Handbook of Organic Conductive Molecules ami Polymers, H.S. Nalwa, ed.,Vol. 4,1997, Figs. 10.13, 10.15a, 10.18, 10.36. Reproduced with permission of John Wiley Sons, Ltd., Chichester. UK.)...

In 1979, Diaz et al. produced the first flexible, stable polypyrrole (PPy) film with high conductivity (1(X) Scm ). The substance was polymerized on a Pt-electrode by anodic oxidation in acetonitrile. The then known chemical methods of synthesis " usually produced low conductivity powders from the monomers. By contrast, electropolymerization in organic solvents formed smooth and manageable films of good conductivity. Thus, this technique soon gained general currency, stimulating further electropolymerization experiments with other monomers. In 1982, Tourillon... 

Fig. 7. Cyclic voltammograms for the oxidation of polyacetylene (PA), polypyrrole (PPy) and polyqnaterthienyl (PQTh)...

Another convenient way to disperse platinum-based electrocatalysts is to use electron-conducting polymers, such as polyaniline (PAni) or polypyrrole (PPy), which play the role of a three-dimensional electrode.In such a way very dispersed electrocatalysts are obtained, with particle sizes on the order of a few nanometers, leading to a very high activity for the oxidation of methanol (Fig. 10). 

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. 

Yoon el al. [112] reported an all-solid-state sensor for blood analysis. The sensor consists of a set of ion-selective membranes for the measurement of H+, K+, Na+, Ca2+, and Cl. The metal electrodes were patterned on a ceramic substrate and covered with a layer of solvent-processible polyurethane (PU) membrane. However, the pH measurement was reported to suffer severe unstable drift due to the permeation of water vapor and carbon dioxide through the membrane to the membrane-electrode interface. For conducting polymer-modified electrodes, the adhesion of conducting polymer to the membrane has been improved by introducing an adhesion layer. For example, polypyrrole (PPy) to membrane adhesion is improved by using an adhesion layer, such as Nafion [60] or a composite of PPy and Nafion [117],... 

Lately, the accelerating effect of functionalized polypyrrole (PPy) composites consisting of ACF/PPy/AQDS is studied during the biological decolorization processes of azo dyes [50]. This study suggests that ACF/PPy/AQDS play a good catalytic role and accelerate the reductive decolorization of different azo dyes by an anaerobic consortium. But their use in the practical full-scale wastewater treatment still needs to be proved in the future studies. 

In 1985 Jakobs et al. studied polypyrrole (PPy) covered platinum and gold electrodes for the ORR,167,168 One interesting result of the work was that, compared to a bare gold electrode, the PPy covered gold reduced oxygen at a lower overpotential.168 Further, the PPy covered electrodes, when in the oxidized state, catalyzed peroxide decomposition and thus improved selectivity to water.168... 

Fig. 1 Building units of conducting polymers, (1) polyacetylene (PA) (2) polypyrrole (PPy), polythiophene (PTh), polyfurane (PFu) (3) polyphenylene (PP) (4) polyaniline (PANI) 5 polyindole (PIND) (6) polycarbazole (PCaz) (7) polyazulene (Paz) (8) polynaphthalene (PNa) (9) polyanthracene (PAnth) (10) polypyrene (PPyr) (11) polyfluorene (PFiu) (12) poly(isothionaphthalene) (PITN) (13) poly(dithienothiophene) (14) poly(thienopyrrole) (15) poly(dithienylbenzene) (1G) poly(3-alkylthiophene) (17) poly(phenylene vinylene) (18) poly(bipyrrole) (PBPy), poly(bithiophene) (PBT) (19) poly(phenylenesulfide) (20) 4-poly(thienothiophene) (21) poly(thienyl vinylene), poly(furane vinylene) (22) poly(ethylenedioxythiophene) (PEDOT).

Comparable to thiophene, pyrrole is a five-membered heterocycle, yet the ring nitrogen results in a molecule with distinctly different behavior and a far greater tendency to polymerize oxidatively. The first report of the synthesis of polypyrrole (PPy) 62 that alluded to its electrically conductive nature was published in 1968 [263]. This early material was obtained via electrochemical polymerization and was carried out in 0.1 N sulfuric acid to produce a black film. Since then, a number of improvements, which have resulted from in-depth solvent and electrolyte studies, have made the electrochemical synthesis of PPy the most widely employed method [264-266]. The properties of electrosynthesized PPy are quite sensitive to the electrochemical environment in which it is obtained. The use of various electrolytes yield materials with pronounced differences in conductivity, film morphology, and overall performance [267-270]. Furthermore, the water solubility of pyrrole allows aqueous electrochemistry [271], which is of prime importance for biological applications [272]. 

Garcia et al., 1998 [107] Fructose Dietetic products Fructose 5-dehydrogenase/in a polypyrrole (PPY) film Platinum electrode/ +0.25 mV vs. Ag/AgCl Sodium ferricyanide... 

Two nitrogen-containing electroactive polymers, polypyrrole (PPY) [21] and polyaniline (PAN) [22], have been of particular interest because of their environmental stability, high electrical conductivity and interesting redox properties associated with the chain heteroatoms. More importantly, PAN has been found to exhibit solution processability [23, 24] and partial crystallinity [25,26]. 

It has been shown that the thickness of the polypyrrole (PPy) film has a significant effect on the electrode performance.17 Figure 6 shows the dependence of the response of PPy/PQQ modified electrode to 10 mM DMAET (A) and 10 mM DEAET (B) as a function of PPy film thickness. As film thickness increases the oxidation current increases for both DMAET and DEAET, presumably due to increases in the amount of PQQ loaded in the PPy film. The maximum current for the oxidation of PQQH2 is observed when 200 nm films are used. When the PPy film thickness was larger then 200 nm a decrease in the sensor response was observed, which could be due to increased resistance (R ) of the thicker film. The optimum 200 nm PPy film thickness was used to characterize the performance of the electrode for amperometric detection of thiols. 

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