The functionality of ionic electroactive polymer (IEAP) actuators is due to the mobility of ions within the ionic membrane and polymer-metal nanostructure (PMNS). The ions are sourced by uptake of electrolyte (aqueous or ionic liquid) into the PMNS, and are mobilized when subjected to an external electrical stimulus. Thus far, the common understanding of the actuation mechanism in IEAP actuators has been that mobility of ions provided by the electrolyte is the primary origin of the mechanical response. Nafion, used as the backbone structure of most IEAP actuators, is an ion permeable polymer with sulfonate end groups and proton counterions. In this work, we have shown that the counterions of Nafion have significant effect on the performance of IEAP actuators and that actuation magnitude, direction and temporal response are closely related to the type of counterions of Nafion. We have studied samples consisting of Nafion in its original (protonated) form and Nafion with 1-ethyl-3-methylimidazolium (EMI) counterions and have shown that the counterions participate in the actuation process and influence the performance of the IEAP actuators. To further scrutinize the relation between polymer counterions and ions sourced by electrolytes, samples with proton (H) or EMI counterions were tested with different electrolytes. It was observed that systems with larger counterions exhibit larger cationic actuation magnitude, suggesting participation of the positively charged counterions in the generation of cationic actuation.

Ionic interactions of ionic membrane and polymer-metal nanostructures in ionic electroactive polymer soft actuators

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.