LAUSR

Electromechanical (EM) coupling—the conversion of energy between electric and mechanical forms—in ferroelectrics has been used for a broad range of applications. Ferroelectric polymers have weak EM coupling that severely limits their usefulness for applications. We introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it. Under a low–dc bias field of 40 megavolts per meter, the relaxor tetrapolymer has an EM coupling factor (k33) of 88% and a piezoelectric coefficient (d33) >1000 picometers per volt. These values make this solution-processed polymer competitive with ceramic oxide piezoelectrics, with the potential for use in distinct applications. Description Polymer piezo The best-performing piezoelectric materials are oxide ceramics, which are widely used for sensors and actuators. X. Chen et al. added two additional components to poly(vinylidene difluoride) trifluoroethylene to improve the electromechanical coupling (see the Perspective by Wang and Liao). The resulting tetrapolymer has piezoelectric properties that are dramatically improved and it appears to be competitive with traditional oxides. The pliability and relative ease of fabrication of this tetrapolymer piezoelectric makes it attractive for a range of interesting applications. —BG An improved polymer has properties that make it competitive with commercially available ceramic piezoelectrics.