Influence of conductive network composite structure on the electromechanical performance of ionic electroactive polymer actuators

The influence of the nanostructure of the conductive network composite (CNC) on the performance of ionic electroactive polymer (IEAP) actuators has been examined in detail. We have studied IEAP actuators consisting of CNCs with different volume densities of gold nanoparticles (AuNPs) and the polymer network. Varying the concentration of AuNPs in CNC thin films was used as a means to control the CNC-ion interfacial area and the electrical resistance of the CNC, with minimum effect on the mechanical properties of the actuator. Increasing the interfacial area and reducing the resistance, while maintaining porosity of the composite, provide means for generating motion of more ions into the CNC at a significantly shorter time, which results in generation of strain at a faster rate. We have demonstrated that cationic strain in actuators with denser CNCs is improved by more than 460%. Denser CNC structures have larger interfacial areas, which results in attraction/repulsion of more ions in a shorter time, thus generation of a larger mechanical strain at a faster rate. Also, time-dependent response to a square-wave voltage was improved by increasing the AuNP concentration in the CNC. Under 0.1 Hz frequency, the cationic strain was increased by 64% when the AuNP concentration was increased from 4 to 20 ppm.