Effects of applied stress and long-term stability on PPy(CF3SO3) linear actuators

The actuation performance of PPy(CF3SO3) films, in the free-standing form, has been characterized in aqueous NaPF6 electrolytes during potential step experiments. Actuation strains of up to 7.5% were observed due to anion insertion at more positive potentials. The actuation strain decreased as the applied stress was increased up to 12 MPa, and then remained constant at above 4% up to the maximum applied stress of 28.8 MPa. A relatively large creep was observed in the case of an applied stress of 28.8 MPa. The film could be cycled more than 1500 times with the retention of 18% of the initial strain level.