Electropolymerization and dual actuating-sensing capabilities of polypyrrole composites with two organic particles

Polypyrrole film composites were galvanostatically electropolymerized (EP) from suspensions of either chemically oxidized polypyrrole (CP) or carbide-derived carbon (CDC) particles, generating EPCP and EPCDC composite films. In addition to these particles the material includes anions of phosphotungstide acid (PTA), used to prepare the particle suspensions and dodecylbenzenesulfonate (DBS^-) used as electrolyte. The final composite materials were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy, with their conductivity and density also measured. The dual actuating-sensing capabilities of the of the films (linear actuators) were quantified from their electrochemomechanical responses in organic electrolyte solution. Three different potential ranges were explored by cyclic voltammetry and square potential waves. The EPCP actuator, which expands upon reduction (cation-driven actuation) achieves a maximum strain of 2.6 %, while the EPCDC, which expands by oxidation (anion-driven) showed a maximum strain of 7.2 %. These values surpass those reported in the literature for other cation- or anion-driven PPy composites. The EPCP´s actuating charge density was 1.5–1.7 times higher than that of the EPCDC actuators. Despite the high material complexity improving dual and simultaneous actuating-sensing capabilities were achieved. In the studied potential ranges, both actuators work under charge balance, as proved by the coulovoltammetric responses. Future studies will explore the expected increase in actuator durability and charge storage capacity.