Conductivity polypyrroles

In 1979, the formation of conductive polypyrrole films by the electrochemical oxidation of pyrrole was reported for the first time This work has stimulated intense and fruitful research in the field of organic conducting polymers. Further important conductive polymers are polythiophene, polyaniline and polyparaphenylene. The development and technological aspects of this expanding research area is covered... 

Due to its electronic conductivity, polypyrrole can be grown to considerable thickness. It also constitutes, by itself, as a film on platinum or gold, a new type of electrode surface that exhibits catalytic activity in the electrochemical oxidation of ascorbic acid and dopamine in the reversible redox reactions of hydroquinones and the reduction of molecular oxygen iV-substituted pyrroles are excellent... 

The amperometric dehydrogenase sensor for ethanol consists of a platinum electrode on the surface of which alcohol dehydrogenase (ADH), Meldra blue (MB) and NAD are immobilized with a conductive polypyrrole membrane as schematically illustrated in Fig.24. 

Bruno FF, Nagarajan R, Roy S, Kumar J, Samuelson LA (2003) Biomimetic synthesis of water soluble conductive polypyrrole and poly(3,4-ethylenedioxythiophene). J Macromol Sci A Pure Appl Chem A 40(12) 1327-1333... 

Fig. 122. Polymerization of pyrrole monomer in a preformed ferric stearate multilayer film (black dots represent electrically conducting polypyrrole) [764]...

Tarasevich (1986) has claimed a 100-day life for glucose oxidase direcdy adsorbed on his electronically conducting polypyrrole. 

Ghosh et al. [14] hypoxanthine, respectively Hypoxanthine Fish Catla- Xanthine oxidase, Conducting polypyrrole Ferrocene carboxylic acid... 

H. Shinohara, G. F. Khan, and M. Aizawa, Electrochemical oxidation and reduction of PQQ using a conducting polypyrrole-coated electrode, J. Electroanal. Chem. 304, 74-84 (1991). 

Propagation of the polymerization is seen by a change in color of the LB film from the semitransparent white of the precursor LB film to the blackish green or reddish brown of the conductive film. Several other methods were demonstrated to obtain conductive polypyrrole LB films [86,87]. The conductive LB films of polyaniline [85,87] and poly thiophene [85,88—93] were also reported. For the latter LB films, a maximum conductivity of 5 S/cm was obtained by NOPF6 doping [91]. 

Fig. 4.117. Qualitative do resistance response characteristic at room temperature of a conductive polypyrrole sensorto pulses of amnnonia and nitrogen dioxide (J. J. Miasik, A. Hooper, P. T. Mosely, and B. C. Tofield, Electronically Conducting Polymer Gas Sensors, in Conducting Polymers, Luis Alcacer, ed., Reidel, Dordrecht, The Netherlands, 1987).

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... 

Chemically Modified Conducting Polypyrrole Film Electrodes... 

Recognizing that the conducting polypyrrole films can be chemically modified (.1,2), the phenyl substituent assumes a particularly important role because it provides a means of introducing a wide selection of functional groups into the polymer. With this objective in mind, we have prepared a series of N-arylpyrrole polymers and find the thin poly-N-(p-nitrophenyl)pyrrole films of particular interest because they combine the electroactive properties of nitrobenzene and polypyrrole. With this combination, the polymer can be switched electrochemically between the cationic, neutral, and anionic form. 

Procedure proposed by Papirer et al. [28,37-39,53] was used in characterization of silicas, modified silicas, oxides and minerals. Authors of refs. [23-28,30,54] used this method for characterization of carbon fibers, solid polymers, i.e. conducting polypyrroles, polycarbonates and poly (dimethacrylates), respectively. Voelkel and Krysztafkiewicz [55] characterized silicas modified by organic compounds. 

Electron conducting polypyrrole BLMs have been used for developing glucose sensors [80]. Similarly, s-BLMs have been employed for the same purpose. The same principle was recently used to prepare a simple and fast... 

Furthermore, the functionalization of conducting polypyrrole films has been used for formation of surfaces suitable to link enzymes or other proteins covalently [26]. 

Because of its high stability and its good electrical conductivity polypyrrole (PPy) can be used in many technical applications, e.g., in the field of microchips and microstructured electronic devices. Polypyrrole can also be used as a material in sensor technology. The interaction of different gases wifii the polymer structure can be detected by the paramagnetic resonance [1] or electrical conductivity measurements... 

A great amount of work has been aimed at obtaining high conductivity polypyrrole films deposited by... 

Dhawan and Trivedi [127] studied the thermal stability of conducting polypyrrole film, grown on the FeCU spray-coated polyvinylacetate film, exposed to pyrrole vapours under mild vacuum. The thermogravi-metric analysis data for the conductive polypyrrole composite showed its stability up to I50°C and after that a continuous weight loss was observed up to 450°C implying the breakdown of the host polymer, polyvinylacetate matrix. The differential thermal analysi.s of the composite also showed first inflection at 205°C followed by a major transformation at 296°C. 

The LB technique may also be combined with solid-state chemistry methods to produce novel molecular architectures. For example, a network of conductive polypyrrole (molecular wires ) may be obtained in a fatty acid matrix [37, 38]. First, monolayers of the iron salt of a long-chain fatty acid (e.g., ferric pahnitate) are assembled on an appropriate substrate. The multilayer film is then exposed to saturated HCl vapor at room temperature for several minutes. During this process, a chemical reaction transforms the fatty acid salt into layers of ferric chloride separated by layers of fatty acid. In the third and final step, the film is exposed to pyrrole vapor and a reaction occurs between the pyrrole and the ferric chloride, producing polypyrrole distributed within the multilayer assembly. 

Lee, K., R. Menon, C.O. Yoon, and A.J. Heeger, Reflectance of conducting polypyrrole Observation of the metal insulator transition driven by disorder. Physical Review B, 1995. 52 pp. 4779... 

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