A study of electrochemical behaviour of polypyrrole films in highly concentrated aqueous electrolytes

Abstract

Polypyrrole polymer films doped with large surfactant anions, dodecyl benzene sulfonate, (PPy/DBS) can be used as soft actuators and their performance and stability depend on the type of the cycling electrolytes and their concentrations. In an attempt to discover suitable electrolytes for such actuators, the diffusion of counter ion into PPy/DBS films in various aqueous electrolytes has been investigated in this work. The PPy/DBS films were cycled at different scan rates in various alkali halide aqueous electrolytes having concentrations ranging from 0.1-1 M in order to determine the diffusion coefficients of alkali halide ions. The effective diffusion coefficients were found to increase with the concentration of the electrolytes and decrease with the increase in size of cations. Since the effective diffusion coefficient of counter ions is a direct measure of the speed of response when such films are used as electrodes in artificial muscles or in batteries, this finding is especially useful for the design of fast actuators based on PPy/DBS polymers.