Enhanced electrochemical strain in polypyrrole films

Electrochemomechanical characteristics of polypyrrole (PPy) films, electrodeposited from tetra-n-butylammonium trifluoromethane-sulfonate dissolved in methyl benzoate (PPyFMS), have been investigated using a simultaneous measurement of electrochemomechanical deformation (ECMD) with cyclic voltammetry (CV) by comparing with PPy films deposited from p-phenol sulfonate in aqueous media (PPyPPS). The ECMD magnitude of PPyFMS film was reached around 9% at 1st cycle and was decreased to be about 3.2% at 20th cycle with electrochemical cycling in 1 M NaPF6. While in 1 M NaCl solution, the ECMD magnitude was 1.9% at 20th cycle in CV measurement. In the case for the PPyPPS film, ECMD magnitude at 20th cycle was around 0.8% and 1.1% in 1 M NaPF6 and 1 M NaCl solutions, respectively. The results indicate that the combination of electrolytes employed in both the electrodeposition and the device actuation plays the very important role for achieving the enhancement of ECMD magnitudes. In the case of ECMD behaviors, it was found that the electrolyte used in the film actuation determines the ECMD characteristics.