Polypyrrole conduction

Figure 3.76 (a) Plot of the log of the polypyrrole film conductivity polymer potential, , fora 10mV potential difference applied across a 13.9pm-thick film in 0.1 M tetraethylammonium tetrafluoroborate/CH3CN. (b) Plot of polypyrrole conductivity vs. fractional charge per pyrrole monomer subunit (qimm) in 0.1 M tetraethylammonium tetrafluorobnrate/CH3CN From Feldman et at. (1985). Copyright 1985 American Chemical Society. 

Several studies have focused on the mode of formation and properties of polypyrrole polymers. Studies of the effects of temperature on polypyrrole conductivity have shown that the polymer formed by electropolymerization of pyrrole and camphor sulfonate as dopant at low temperature has higher conductivity and is stronger than that formed at higher temperatures. X-ray scattering shows that interlayer distance increases with increasing temperature <2002IAS155>. 

The discovery that doped forms of polypyrroles conduct electrical current has spurred a great deal of synthetic activity related to polypyrroles [216-218], Reviews are available on various aspects of the synthesis and properties of polypyrroles [219,220]. In addition, summaries of important aspects of polypyrroles are included in several reviews on electrically conducting polymers [221-226]. Polypyrrole has been synthesized by chemical polymerization in solution [227-231], chemical vapor deposition (CVD) [232,233], and electrochemical polymerization [234-240]. The polymer structure consists primarily of units derived from the coupling of the pyrrole monomer at the 2,5-positions [Eq. (84)]. However, up to a third of the pyrrole rings in electrochemically prepared polypyrrole are not coupled in this manner [241]. 

F. Granato, A. Bianco, C. Bertarelli, and G. Zerbi, Composite polyamide 6/polypyrrole conductive nanofibers, Macromolec. Rapid Commun., 30, 453 58 (2009). 

Polyamide 6 (PA-6)/polypyrrole-conductive nanofibers, prepared by the pol5merization of pyrrole on the fiber surface, were studied. A solution of PA-6 added with ferric chloride in formic acid was elec-trospun and the fibers were exposed to pyrrole vapours. Potyp3UTole was formed on the fiber surface. Polypyrrole-polyethyleneoxide... 

Park, J.W., et al. 2000. Characteristics of organic electroluminescent devices using polypyrrole conducting layer and undoped conjugated polymer layer. Thin Solid Films 363 259. 

DellaSanta, A., D. De Rossi, and A. Mazzoldi. 1997. Performance and work capacity of a polypyrrole conducting polymer linear actuator. Synth Met 90 93. 

Pioneering works on functional molecules incorporating conducting polymers firstly demonstrated them as modified electrodes, on which redox molecules such as ruthenium tetraoxide [1] for photo-oxidation of water, mesotetrakis (4-sulphonatophenyl)porphyrin cobalt [2] and iron phthalocyanine [3] for redox catalysis, were incorporated chemically or electrochemically in polypyrrole conducting polymer. They suggested that functionalized conducting polymers should show the native function of a functional molecule while maintaining the native conductivity without a big decrease. 

Yamato, H., Wemet, W., Ohwa, M., and Rotinger, B Characterization of thermoplastic sulfated poly(b-hydroxyethers)/polypyrrole conducting composites, Synth. Metals, 55-57, 3550-3555 (1993). 

The pH-dependent nature of polypyrrole conductivity was used as the basis for biosensors using hydrolases and in some cases oxidases. A sensor for penicillin was formed by immobilizing penicillinase (E.C. 3.5.2.6.) on polypyrrole-coated microelectrode array [100]. The production of penicilloate acidified the local microenvironment, resulting in a change in polypyrrole conductivity, which was measured between microelectrodes on the array (Fig. 7). Sensors for urea and creati-... 

The procedure for preparing fibrillar/microporous polypyrrole membranes is illustrated schematically in Figure 2.. The membrane-coated convex Pt disk working electrode (Figure 3) is immersed into a solution containing the monomer (pyrrole), which is electropolymerized as described above. Ideally (see below) polypyrrole is only synthesized in the pores of the host membrane a Nuclepore/polypyrrole conductive composite membrane is obtained (Figure 2). Polymerization was terminated before the conductive polymer fibrils reached the Nuclepore/solution interface. 

Polythiophene and poly(3-alkylthiopene) are not so stable in the anion-doped state as polypyrrole. Conductivity decreases rapidly during storage. This is a serious drawback to the industrial application of polythiophenes. A method to improve stability is to decrease the oxidation potential of polymer. Introduction of a methoxy group on a thiophene ring reduces the oxidation potential, thus poly(3-methoxythiophene) is stable in the doped state. Another method to improve stability is to make room for the accommodation of dopants. This is a kind of free-volume theory. Poly(3,3"-dialkyl-2,2, 5 -2"-bithiophene) is very stable in the doped state. This is due not only to the... 

Where Tq and are known as Mott parameters and depend on the type of counterion used. To understand the conduction mechanism below 100 K, the Sheng model can be applied to the analysis of the temperature dependence of polypyrrole conductivity [234]. This model takes into consideration both hopping and... 

On the other hand, the observed nonlinear relationship between polypyrrole conductivity and oxidation state may be determined by different limiting factors depending on the film oxidation state. Various con-... 

A conductimetric pH sensor based on a polypyrrole chloride thin film has been developed. Impedance spectroscopy has been used to investigate the complex admittance of the device when exposed to aqueous solutions of different pH. The experimental data have been fitted to the theoretical response of an equivalent electrical network of capacitors and resistors. It has been found that the polypyrrole conductivity shows a good selective response to pH. This study has provided an understanding of the electrical behaviour and of the complex admittance spectra of a simple thin-film electrode system and could be a useful aid for the development of... 

Della Santa A, De Rossi D, Mazzoldi A (1997) Performance and work capaeity of a polypyrrole conducting polymer linear actuator. Synth Met 90 93-100 Ding J, Liu L, Spinks GM, Zhou D, Wallace GG, Gillespie J (2003) High performance conducting polymer actuators utilising a tubular geometry and helical wire interconnects. Synth Met 138 391-398... 

Liao YH, Chou JC (2008) Comparison of polypyrrole-conducting polymer and Ag/AgCl reference electrodes Used for ruthenium dioxide pH electrode. J Electrochem Soc 155 ... 

Ruckenstein, E. and J. H. Chen, Polypyrrole Conductive Composites Prepared by Coprecipitation. Polymer, 1991, 32(7), 1230-1235. 

ElKaoutit M, Naggar AH, Naranjo-Rodriguez I, Dominguez M, de Cisneros JLH-H. Electrochemical AFM investigation of horseradish peroxidase enzyme electroimmobilization with polypyrrole conducting polymer. Synth Met 2009 159 541 545. 

PE blends was promoted by the polypyrrole conducting phase inside the composite membranes [38]. It has also been shown that higher wettability of the polyaniline and polypyrrole coated microporous PE membranes provided better penetration of an aqueous electrolyte solution into the pores, and thus enhanced the transport of ions through the membranes [27],... 

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