The effects of electrode surface morphology on the actuation performance of IPMC

It is generally understood that increasing the specific surface area of the electrodes of IPMC leads to improved electromechanical performance of the material. Most physics based models compensate the effect of high surface area of the electrodes by increasing both diffusion constant and dielectric permittivity values, while using flat electrode approximation in calculations. Herein, a model was developed to take into account the shape and area of the electrodes. High surface area of the electrodes in the model was achieved by designing 2D polymer-electrode interface as a Koch fractal structure – different generation depths and both unidirectional and random directional generations were studied. The calculations indicate that increasing the generation depth of fractals, thus surface area of the electrodes results in more overall transported charge during the actuation process. Based on the model, the effect of the specific surface area of the electrodes on the electromechanical performance was experimentally investigated. IPMCs with different Pd-Pt electrode structures were prepared and their electromechanical and electrochemical properties were examined and discussed. The methods to manipulate the surface structure of Pd-Pt electrodes were proposed.