The influence of electrodeposited conducting polymer electrode structure on the actuation performance of muscle-like ionic actuators

This study demonstrates the influences of physical and electrochemical characteristics of conducting polymer (CP) film as electrode material on the actuation performances of ionic actuators which is of considerable interest for increasing the application of metal-free ionic actuators in different fields. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polypyrrole (PPy) were applied as electrode materials in fabrication of metal-free Nafion-based electromechanical actuators. These polymers were electrochemically deposited on both surfaces of polymeric membrane and variations in physical, electrochemical and electromechanical characteristics of actuators were followed as a function of the applied polymer type. Pt-electrode Nafion based actuators were prepared as standard. Electrochemical studies revealed that the mechanism of actuation is mainly related to double-layer capacitance (Cdl) and that faradic capacitance (CF) plays less significant role. PPy-electrode actuators showed higher ion and water permeability due to formation of thinner electrode layers with finer morphology. The largest tip displacement (25 mm) was obtained in PPy-electrode actuators, in response to 6 V dc potential. These actuators exhibited the highest specific capacitance of 146.26 m F.cm−2 and capacitance retention of 87.41% after 100 cycles. The electro-mechanical energy efficiency and the maximum tip displacement of PPy-electrode actuators were 46.42% and 31.57% higher than that considered for PEDOT:PSS-electrode actuators, respectively.