Sandwich-structured Co3[Co(CN)6]2/P(VDF-HFP) piezoelectric composites with superior electromechanical activity

The development of piezoelectric polymers with superior electromechanical performance is a demand in the areas of flexible sensors, actuators and tissue engineering, among others. In this work, we reported a novel sandwich-structured piezoelectric composites comprising of poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] and Prussian blue analogs Co₃[Co(CN)₆]₂ with excellent electromechanical activities. The large specific surface area, unique three-dimensional porous nanostructure and redox behavior of Co₃[Co(CN)₆]₂ appeared to significantly promote the interfacial coupling effect within P(VDF-HFP), resulting in enhanced electromechanical response. Moreover, the sandwich structure topological design would enlarge the interfacial coupling effect, strengthen the breakdown strength and consequently raise the electromechanical performance. For instance, a maximum piezoelectric coefficient d₃₃ of ~ 41 pC/N can be achieved in the sandwiched composites at a loading of 0.8 wt%, which is 1.78 times that of pure P(VDF-HFP). Furthermore, the sandwiched composites possess superior electromechanical coupling factor k₃₃ up to 0.215, while that of pure P(VDF-HFP) is only 0.134.