Electrogenerated polypyrroles properties

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. 

Polypyrrole can be deposited under potentiostatic or galvanos-tatic conditions and by potential or current sweep or pulses. In any case, the applied electrical conditions introduce effects on both the structme and the properties of the electrogenerated polypyrrole films and on the rate of polymer production. From electrochemical preliminary studies of the electrode in the absence and... 

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. 

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. 

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). 

The choice of an appropriate electrolyte for the doping of polypyrrole during electrochemical polymerization can improve the mechanical properties of the films obtained. Thus, polypyrrole films electrogenerated in the presence of large electrolytes, as /7-toluensulpho-nate, tosylate, benzene sulfonate, etc., yield flexible films with tensile strengths similar to polystyrene [113]. We can extrapolate this behaviour by combining the... 

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