Chemical vapor driven polyaniline sensor/actuators

Porous polyaniline (PANI) asymmetric membranes were prepared using phase inversion technique and a density gradient was found along the cross-section of the membrane. A chemical vapor triggered monolithic actuator was constructed based on the PANI membrane. It was found that the monolithic actuator bends from dense side to porous side in organic vapor and recovers to its original position in air: The actuator shows different bending behavior in different vapors with the most extensive and the fastest bending movement observed in THF vapor. The bending-recovery movement is believed to be caused by the sorption-desorption of organic vapor, which leads to volume deformation that is density dependent. The dense side shows a greater volume expansion than the porous side after the sorption of organic vapors, which causes a bending movement towards then porous side, and the desorption of the organic vapor from the membrane prompts it to recover to its original position.