Examination of the Motion Property and Bending Mechanism of Polypyrrole Fiber Actuator

Abstract

Cylindrical polypyrrole (PPy) fibers were electrochemically polymerized in a Teflon slender pipe. The PPy fiber could be cut into small rectangular strips and the strips were electrochemically characterized. The PPy strip can be used as an actuator, because a bending behavior was observed during oxidation/reduction cycles. That is, the strips bend toward the outer surface, which contacted with the Teflon pipe during polymerization, upon reduction, and revert upon oxidation. We have investigated the bending behavior of the PPy actuator in various electrolytes and have found that incorporation of cations into PPy upon reduction plays a key role in the bending behavior. A mechanism of the bending behavior based on the cation incorporation as well as the anisotropic volume change upon doping is proposed.