Analysis of water and proton fluxes in ion-exchange polymer-metal composite (IPMC) actuators subjected to large external potentials

An analysis is conducted of a novel ion-exchange polymer-metal composite (IPMC) actuator under large external voltage. The model is simplified to a three-component system comprised of a fixed negatively charged polymeric matrix, protons, and free water molecules within the polymer matrix. The proposed coupled model includes mass transport in the membrane, chemical reactions at boundaries, and deformation as a function of a concentration of water molecules. The electrochemical process occurring at both electrodes are the boundary conditions analyzed during the deformation of the actuator in a regime of large voltage (over 1.2 V). This coupled model successfully captures the stress relaxation phenomenon due to water redistribution governed by diffusion. The fabrication process and testing apparatus are also described. Comparison of simulations and experimental data showed good agreement.