Effects of Cu2+ Counter Ions on the Actuation Performance of Flexible Ionic Polymer Metal Composite Actuators

The resistance of Ionic Polymer Metal Composite (IPMC) electrodes plays an important role in the actuation performance of IPMC actuators. Owing to crack formation on the surface of platinum electrode, the surface resistance of the electrode increases, which greatly limits its actuating performance. In this paper, we proposed a new method of dynamic self-repair electrodes by exchanging Cu2+ into the IPMC basement membrane. IPMC actuators with Cu2+ were prepared and the actuation performance in the air was subsequently measured. Compared with conventional IPMC actuators containing Li+ counter ions, those containing Cu2+ counter ions exhibited 2 times –3 times larger displacement and 2 times–3 times bigger blocking force. In the morphology observation, we found that many small copper particles scattered in the middle of cracks after several bending cycles, which leads to an obvious decrease in electrode resistance. In the Cyclic Voltammetry (CV) scan measurement, we observed that the oxidation reaction of copper alternates with reduction reaction of copper ions with the change of voltage polarity, which was a dynamic process. Based on these analyses, it is concluded that the presence of Cu2+ can repair the damaged electrodes and induce lower electrode resistance, thus leading to the performance improvement of actuation.