Behaviors of Polypyrrole Soft Actuators in LiTFSI or NaCl Electrolyte Solutions Containing Methanol

Abstract

Organic soft linear actuators were fabricated using galvanostatic electropolymerization of the polypyrrole (PPy) thin film using a methyl benzoate electrolyte solution of N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide. The electrochemical deformation behaviors of the PPy actuators were investigated in aqueous solutions of an electrolyte, lithium bis (trifluoromethanesulphonyl) imide (LiTFSI) or sodium chloride (NaCl), containing different concentrations of methanol. The actuating strain of approximately 9% was achieved when the actuator was driven by a potential between –1 and 1 V with the potential sweep rate of 10 mV/s corresponding to 0.0025 Hz in the LiTFSI electrolyte containing 40% to 50% of methanol under a load stress of 0.3 MPa. However, the PPy actuator could not catch up with the higher frequency. On the other hand, the PPy actuator caught up with the potential sweep up to 0.1 Hz in the NaCl solutions with a methanol concentration between 40% and 60% with the expense of the actuating strain to approximately 1%.