A rationally-designed synergetic polypyrrole/graphene bilayer actuator

The development of advanced actuator system strongly depends on the assorted use of unique materials and rational structure design. In the current work, a newly designed bilayer actuator based on a graphene film which has undergone O-2 plasma pretreatment and the conducting polymer polypyrrole (PPy) doped with small anions has been presented. The antithetic expansion-contraction mechanisms of graphene and PPy films under a certain positive or negative potential offer the favorably synergetic function for driving the excellent actuation response of the resultant PPy/graphene bilayer actuator. In response to the variation of electrochemical potentials (e.g., +/- 0.8 V), the PPy/graphene actuator can move to and fro with a large bending angle of ca. 120 degrees despite the limit of electrolyte surface, which is superior to that of the unitary graphene films demonstrated previously, and overcomes the relatively poor mechanical strength of PPy films. Calculations based on an ideal model by only considering the deformation of each constituent layer of the actuator reveal that the bending degree of PPy/graphene configuration could be up to ca. 1600 degrees, suggesting that there is considerable room to further optimize the actuator configuration and improve the actuation performance.