Ionic liquid/polyurethane/PEDOT:PSS composites for electro-active polymer actuators

The transparent ionic liquid/polyurethane (IL/PU) gels were synthesized by addition reaction of polyol and diisocyanate in the presence of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. With increasing the IL content from 0 wt% to 40 wt%, both ionic conductivity and electric-double-layer capacitance increased from 3.1 × 10−5 S cm−1 and 9.6 pF cm−2 to 8.8 × 10−5 S cm−1 and 277 pF cm−2, respectively, while the compression modulus slightly decreased from 0.49 MPa to 0.44 MPa. The IL/PU/PEDOT:PSS composites were fabricated by sandwiching the IL/PU gel between two conductive polymer films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) as soft and flexible electrodes. Upon application of an electric field, the IL/PU/PEDOT:PSS composite showed quick and intensive bending toward anode, where the bending displacement attained 3.8 mm at IL = 40 wt% and 2 V, corresponding to the strain of 0.32%.