Polymers polypyrrole

Figure 4 compares cyclic voltammograms for a redox polymer (poly-[Fe(5-amino-1,10-phenanthroline)3]3+/2+)91 and p-doping and undoping of a conducting polymer (polypyrrole).92 The voltammogram for the redox... 

Figure 4. (A) Cyclic voltammograms over a range of scan rates for a redox polymer (poly-[Fe 5-amino-1,10-phenanthrotme)3]3+/>)91 and (B) p-doping and undoping of a conducting polymer (polypyrrole) (B). [(A) Reprinted from X. Ren and P. O. Pickup, Strong dependence of the election hopping rate in poly-tris(5-amino-1,10-phenan-throline)iron(HI/II) on the nature of the counter-anion J. Electroanal. Chem. 365, 289-292,1994, with kind permission from Elsevier Sciences S.A.]...

The final step entailed coating both the inner and outer surfaces of the LiMn204 tubules with the conductive polymer polypyrrole [125]. It has been shown that such LiMn204/polypyrrole composite electrodes have lower resistance and higher capacity than electrodes prepared from LiMn204 alone [125]. Furthermore, the high porosity and fast (relative to... 

The deposition of a conductive polymer (polypyrrole) into either a track-etched polycarbonate or alumina membrane was either achieved by electrochemical reduc-... 

Recently supercapacitors are attracting much attention as new power sources complementary to secondary batteries. The term supercapacitors is used for both electrochemical double-layer capacitors (EDLCs) and pseudocapacitors. The EDLCs are based on the double-layer capacitance at carbon electrodes of high specific areas, while the pseudocapacitors are based on the pseudocapacitance of the films of redox oxides (Ru02, Ir02, etc.) or redox polymers (polypyrrole, polythiophene, etc.). 

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]. 

More recent studies have focussed on the characterization of the conductive polymer, polypyrrole, and its use as a coating for acoustic wave vapor sensors [74-77]. One advantage of polypyrrole is that it can be generated directly on an... 

Ramanavicius, A., Ramanaviciene, A., Malinauskas, A. (2006). Electrochemical sensors based on conducting polymer-polypyrrole. Electrochim. Acta 51 6025-37. 

An optically active and electroconductive polymeric sorbent was prepared by coating the PS-L-proline-Cu(II) beads with conducting polymer polypyrrole. Applying a potential difference of 1.5 V to the column, racemic lysine and aspartic acid were separated according to their charge characteristics and were simultaneously resolved with respect to their optical isomerism. 

A few groups examined larger systems by in situ STM. Examples include the deposition of polymers, polypyrrole, polyaniline,and polymethylthiophene. Hagenstrom et al. reported studies on imaging of self-assembled monolayers (SAM). "" They showed the possibihty of imaging detailed stmetures, and order-disorder transitions in dependence on electrochemical parameters. 

An interesting application is photosensitized polymerization of pyrrole (431) using [Ru(bpy)3]3 + to give a conducting polymer, polypyrrole (432), in aqueous solution or in a polymer matrix (Scheme 6.205).1236 The acting ground-state electron acceptor, [Ru(bpy)3]3 +, is obtained in the initial electron transfer step between an excited [Ru(bpy)3]2+ and [Co(NH3)5C1]2+ ion. 

Aizawa has studied an enzyme (metal) electrode based on immobilized GOD, which is a redox enzyme [66]. Interfacing in this type of biosensor requires facilitation of electron transfer from the active site of the enzyme protein to the metal electrode. Various methods have been used, such as electron mediators, electron promoters, and molecular wires, to accomplish this purpose. For example, a conducting polymer, polypyrrole, formed by electropolymerization on the electrode surface, was used to form electron wires which can facilitate electron transfers to and from the metal electrode. 

Figure 14-18. Covalent binding of enzymes to the conducting polymer polypyrrole. The reaction sequence shows the functionalization of the electrochemically deposited polymer film by nitration and subsequent electrochemical reduction.

However, such behaviour was not observed in a recent work by Laborde et al. [55], where hydrogen oxidation at a PAni film containing 0.1 mg cm of platinum takes place at low overpotentials as is usual for an electroactive material. In another paper [63] Laborde et al. observed the electro-oxidation of dissolved hydrogen at a co-polymer (polypyrrole-polydithiophene) electrode modified with 0.1 mg cm of platinum, leading to a very small overvoltage (Figure 10.2). 

The principle is to activate molecular oxygen, by the Mn porphyrin entrapped in the conductive polymer (polypyrrole), and thus to form oxo species at the electrode surface. Then, these oxo complexes can oxidize the hydrocarbons or phenol. The catalyst should be regenerated and this can be done by electroreduction at a constant potential (typically at — 0.5 V/SCE in acetonitrile). Moreover, the solution should contain an axial base (i.e. imidazole), and an activator (benzoic anhydride) [165,172]. 

The bandgap of an intrinsically conducting polymer (polypyrrole) has been determined with photocurrent spectra [749]. 

Polyaniline and its substituted derivatives, such as poly(o-toluidine), poly(o-anisidine), poly(N-methylaniline), poly(N-ethylaniline), poly(2,3-dimethylaniline), poly(2,5-dimethylaniline) and poly (diphenylamine) have been reported [36] to show measurable responses (sensitivity 60%) for short chain alcohols (viz., methanol, ethanol and propanol) at concentrations up to 3000 ppm. The change (decrease) in resistance of the polymers on exposure to alcohol vapors has been explained based on the vapor-induced change in the crystallinity of the polymer. Polypyrrole (PPy) incorporated with dodecyl benzene sulfonic acid and ammonium persulfate has been reported to show a linear change in resistance when exposed to methanol vapor in the range 87-5000 ppm [37]. The response is rapid and reversible at room temperature. 

A. Watanabe, M. Tanaka, and J. Tanak, Electrical and optical properties of a stable synthetic metallic polymer polypyrrole. Bull. Chem. Soc. Jpn., 54, 2278-2281 (1981). 

A. Ramanaviciene, W. Schuhmann, and R. Ramanavicius, AFM study of conducting polymer polypyrrole nanoparticles formed by redox enzyme - glucose oxidase - initiated polymerisation, Colloid Surf. B., 48(2), 159-166 (2006). 

K. Yamato and K. Kaneto, Tubular linear actuators using conducting polymer, polypyrrole. Anal. Chim. Acta, 568 (1-2), 133-137 (2006). 

X. Cui, J.F. Hetke, J.A. Wiler, D.J. Anderson, and D.C. Martin, Electrochemical deposition and characterization of conducting polymer polypyrrole/pss on multichannel neural probes. Sens. Actual. A Phys., 93(1), 8-18 (2001). 

Poly 1 -(trimethylsilyl)-1 -propynel Conjugated conducting polymers Polypyrrole Polythiophene... 

Wadhwa, R., Lagenaur, C.F., Cui, X.T., 2006. ElectrochemicaUy controlled release of dexamethasone from conducting polymer polypyrrole coated electrode. J. Controlled Release 110,531-541. 

Hao, L., Zhu, C., Chen, C., Kang, E, Hu,Y., Fan, W., Chen, Z., 2003. Fabrication of silica core-conductive polymer polypyrrole shell composite particles and polypyrrole capsule on monodispersed silica templates. Synth. Met. 139,391-396. 

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