Electrochemical actuator based on monolithic polypyrrole–TiO2 nanoparticle composite film

A polypyrrole (PPy) composite film with a pure PPy zone and a PPy–TiO2 nanoparticle composite zone in its cross-sectional direction was synthesized by direct oxidation of pyrrole successively in an electrolyte with or without TiO2 nanoparticles. The volume content of TiO2 in the composite film was tested to be lower than 0.9%. The actuator fabricated from this monolithic PPy film bends uniformly in two directions with a maximum bending angle larger than 90° and has a high response rate (∼115° s−1 at 1.0 V versus SCE) and a long lifetime (>20,000 cycles) in a 1 M LiClO4 aqueous solution. The high performance of this actuator resulted from the non-delamination and intrinsic asymmetric structure and the high conductivity of PPy film.