Wrinkled polypyrrole electrode for electroactive polymer actuators

As an electrode for a bending-electrostrictive polyurethane actuator, we prepared a wrinkled polypyrrole electrode, expecting the following two effects because the wrinkled electrode could easily elongate by smoothing the wrinkles: (1) conductivity of the electrode would not decrease with the field-induced surface elongation of the actuator, and (2) the electrode would not constrain the actuation. The wrinkled electrode was prepared through in situ deposition of polypyrrole onto the polyurethane elastomer film that was being uniaxially drawn. After the deposition, the film was released from the drawing to make the electrode wrinkle. The conductivity of the wrinkled electrode did not decrease at elongation rates less than 40%. The bending actuation of the polyurethane film with the wrinkled electrode was improved more than twice that as compared with an unwrinkled one. In addition, doping the polyurethane with sodium acetate also improved the actuation. By these improvements, the bending actuation reached 7 mm in radius of curvature within 0.2 s when the applied voltage was 1000 V. (C) 2002 American Institute of Physics.