No abstract

Abstract. Further development of mechanical devices based on conducting polymers; require a precise understanding of their mechanical response, i.e. their control, under a controlled external current. In this work, we show some results for the relation between the electrical current consumed in the electrochemical process and the mechanical work developed by a freestanding polypyrrole strip, when it is subjected to a stretching force (stress). Under these conditions, from the results obtained in this work, we observe how it results almost impossible to predict a straight relationship between mechanical work and current consumed in the electrochemical process. In addition, we will quantify the variation of the mechanical properties of the free standing polypyrrole strip associated with the oxidation state of the polymer by measuring its Young's modulus.

Environmental and electrical variables, as temperature, electrolyte concentration or driving current, influence oxidation and reduction oxidation rates of free-standing polypyrrole/DBSA/ClO 4 -films. Under flow of a constant current for a constant time, decreasing electrical energies are consumed to oxidize or to reduce the film under increasing temperatures or rising electrolyte concentrations. By consuming the same charge under flow of rising constant currents, the consumed electrical energy increases. As conclusion the consumed electrical energy by flow of constant charges during oxidation, or reduction, of the film is a sensor of the electrochemical cell temperature, the electrolyte concentration or the flowing current. Those sensing capabilities seem to be a general property of the electrochemistry of conducting polymers. Any electrochemical based device, as actuators, polymeric batteries, smart membranes, smart drug delivery devices and others, are expected to sense environmental conditions while working. The sensing abilities of a complex actuator constituted by four polypyrrole films, two acting as electrodes (anodes or cathodes) and the other two as counter electrodes (cathodes or anodes, respectively) are presented. Experimental results are equivalent to sensing charge/discharge processes in all polymeric batteries.