Polypyrrole electrogeneration

All the research devoted to the study of the different chemical and physical aspects of polypyrrole electrogeneration and switching is largely justified by the many technological applications of this material. Most applications require films with improved structural and/or electrochemical properties. The last section of the chapter will focus on the relationship between film properties and requirements for applications. 

Oiero, T. F., Santamaria, C., and Bunting, R. K., Kinetic studies of polypyrrole electrogeneration in three solvents, J. Electroanal. Chem, 380, 291-294 (1995). 

Otero, T. E, and Angulo, E., Comparative kinetic studies of polypyrrole electrogeneration from acetonitrile solutions, J. Appl. Electrochem., 22, 369-375 (1992). Otero, T. E, and Rodriguez, J., Parallel kinetic studies of the electrogeneration of conducting polymers mixed materials, composition and properties control, Electro-chim. Acta, 39, 245-253 (1994). 

Figure 10.2. Possible reaction ways for pyrrole-pyrrole linkages in polypyrrole electrogeneration.

Many different materials can be used to build bilayer artificial muscles. Here, for simplieity, we will focus on doped polypyrrole electrogenerated and characterized in presenee of LiClOVcommercial (office) tape bilayer artificial muscles. For that, pyrrole (Fluka) was purified by distillation under vacuum using a diaphragm vacuum pump MZ 2C SCHOTT and stored under nitrogen atmosphere at -10 °C. 

T. F. Otero and E. Angulo, Comparative kinetic studies of polypyrrole electrogeneration from acetonitrile solutions, J. Appl. Electrochem. 22 369 (1992). 

When polypyrrole was electrogenerated from dry acetonitrile electrolytes, a black polymer grew and adhered to the electrode. After a few seconds of electropolymerization, a black cloud was observed around the electrode. The film obtained had poor electrochemical and physical properties. Increasing the water content to 2% (w/w) gives, at 800 mV, films with improved properties. The black cloud around the electrode disappears. 

Figure 12. Model of interfacial reactions proposed for the electrogeneration of polypyrrole from aqueous and acetonitrile solutions. (Reprinted from T. F. Otero and J. Rodriguez, Electrochim. Acta 39, 245, 1994, Figs. 2, 7. Copyright 1997. Reproduced with permission from Elsevier Science.)...

Polypyrrole composites [Fig. 13(d)], electrogenerated from monomeric solutions of polyelectrolytes.82 89... 

Polypyrrole hybrids [Fig. 13(e)], electrogenerated from solutions containing the monomer and a salt of an inorganic macroion or a polyoxide.90-92... 

Diaz AF, Logan JA(1980)Electroactive polyanihne films. JElectroanalChem 111 111-114 Noufi R, Nozik AJ, White J, Warren LF (1982) Enhanced stability of photoelectrodes with electrogenerated polyanUine films. J Electrochem Soc 129 2261-2265 Noufi R, Tench D, Warren LE (1981) Protection of semiconductor photoanodes with photoelectrochemicaUy generated polypyrrole films. J Electrochem Soc 128 2596-2599 Jaeger CD, Fan FRF, Bard AJ (1980) Semiconductor electrodes. 26. Spectral sensitization of semiconductors with phthalocyanine. J Am Chem Soc 102 2592-2598 Gerischer H (1977) On the stability of semiconductor electrodes against photodecomposition. J Electroanal Chem 82 133-143... 

R.E. Ionescu, C. Gondran, L.A. Gheber, S. Cosnier, and R.S. Marks, Construction of amperometric immunosensors based on the electrogeneration of a permeable biotinylated polypyrrole film. Anal. Chem. 76, 6808-6813 (2004). 

Due to the vast achievements in immunosensor development, only few highlights of novel immobilization techniques and investigative detection principles based on electrogenerated polypyrrole films are presented with cholera toxin and hepatitis C Virus (HCV) as exemplary target analyte. 

The development of optical immunosensors for the detection of antibody of HCY was performed by electrogeneration of the photoactive polypyrrole on ITO-modified optical fibers followed by internal light irradiation in the presence of the virus. The resulting layer of HCY can act as an antigen for the detection of the anti-HCV antibody. After the immunoreaction, the subsequent binding of a marker, a secondary peroxidase-labeled antibody, allowed to catalyze a chemiluminescence reaction in the presence of luminol and H202 [59]. 

FIGURE 16.8 (a) Stainless steel electrode partially coated with an electrogenerated polypyrrole film, (b) adhesion... 

Mousty, C. Galland, B. Cosnier, S. Electrogeneration of a hydrophihc cross-hnked polypyrrole film for enzyme electrode fabrication. Apphcation to the amperometric detection of glucose. Electroanalysis 2001,3,186-190. 

Optimization of Electrical and Redox Properties of Electrogenerated Polypyrroles... 

Once the coexistence of different processes during electropolymerization is detected, the final composition and properties of the electrogenerated polypyrroles can be related to the chosen parameters of synthesis. The reverse reasoning is always true and fundamental from a technological point of view on defining a property, specific conditions of synthesis can be selected in order to optimize it. As the electrochemical polymerization of pyrrole involves many experimental variables, adequate control of the polymer synthesis will require analysis of the effects of the individual parameters (electrode, solvent, electrolyte, pH of the solution, temperature, and potential of synthesis) and their interdependence. 

Most poly pyrrole films have been prepared using inert electrodes, such as Pt [27], Au [28], or glassy carbon [29]. The main problem associated with the electrogeneration of polypyrrole onto active metals, such as Ti, Fe, stainless steel, or Al, is related to the interference of the electrochemical behavior of the metal with the... 

The electrolyte concentration employed during synthesis also influences the conductivity of polypyrrole. This has been observed for polypyrrole films electrogenerated on aluminum electrodes, where the conductivity varies from 100 to 320 S cm when the electrolyte concentration (/-butylammonium p-toluenesulfonate salt) increases from 0.05 to 0.3 M [37]. Similar results have been obtained by Satoh et al. [51] using ITO glass electrodes. These higher conductivities should be associated with the higher dopant concentration or the influence of the electrolyte concentration on the polymerization rate. 

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