Electrochemical Creeping and Actuation of Polypyrrole in Ionic Liquid

The electrochemical creeping and actuation of polypyrrole films operated in an ionic liquid are reported. The electrochemical deformation was initiated by the reduction and swelling of the films by 15–20% with soaking in ionic liquid. An electrochemical strain of 3% and a blocked stress of 1.7 MPa showing cation movement were obtained. The film showed creeping at tensile loads larger than 0.5 MPa. The electrochemical strain obtained in a mixed solution of an ionic liquid and propylene carbonate was 15% at the initial stage, showing anion movement together with swelling induced by soaking in solvents. However, the electrochemical strain became negligible after several electrochemical cycles, resulting from the loss of electrochemical activity and conductivity upon swelling.