A robotic multiple-shape-memory ionic polymer-metal composite (IPMC) actuator: modeling approach

Abstract

The multiple-shape-memory ionic polymer–metal composite (MSM-IPMC) actuator can demonstrate complex 3D deformation. The MSM-IPMC has two distinct characteristics, which are the electromechanical actuation effect and the thermal-mechanical shape memory effect. The bending, twisting, and oscillating motions of the actuator could be controlled simultaneously or separately by means of thermal-mechanical and electromechanical transduction. In this study, a theoretical model for the MSM-IPMC was developed and experimentally investigated. Based on previous studies on the electromechanical actuation effect of ionic polymer–metal composite (IPMC), a comprehensive physics-based model of MSM-IPMC which couples the actuation effect and the multiple shape memory effect was developed. To verify the model, an MSM-IPMC sample was prepared and used in experimental testing. The simulation results were shown to be in good agreement with the experimental results obtained. The multiple shape memory and recovery rate of three different polymers, namely the Nafion, Aquivion and GEFC of different ions, which are the hydrogen, lithium and sodium, were also tested. Based on the results, it is shown that all the polymers demonstrate the multiple shape memory effect with varying amounts of programmable shapes. The ion type was shown to have an influence on the broad glass transition range of the polymers, which in turn dictated the number of possible programmable shapes for each membrane. The current study is beneficial for the better understanding of the multiple shape memory effect of MSM-IPMC.