Ionic Electroactive Polymer Actuators Using Quaternary Ammonium Iodide (QAI) Containing Hydrogels Operational at Low Voltages

Quaternary ammonium iodide (QAI)-containing hydrogels with different alkyl side chain lengths were synthesized and used to develop ionic electroactive strip actuators. The strip bent at relatively low voltages, exhibiting a 5.0 mm bending displacement over the 30 mm strip length at 0.6 V, for example. The bending displacement largely depended on the applied voltages and alkyl side chain lengths. The anticipated bending mechanism is the movement of the iodide anions toward the anode, thereby driving volume contrast in the strip near the anode (volume expansion) and cathode (volume contraction). This mechanism was experimentally confirmed by monitoring the location of the iodide anions in the strip by using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) and confocal microscopy. The obtained QAI-containing actuators are operational at relatively low voltages and in water-containing environments and also have antimicrobial properties, which would be useful for biological environment applications.