High dielectric constant poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) for capacitive pressure and bending sensors

Abstract

Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene), P(VDF-TrFE-CFE), samples were prepared by solvent casting by varying polymer concentration and solvent evaporation temperature. Different sample morphologies were obtained depending on the processing conditions, as well as different physical-chemical properties such as degree of crystallinity, mechanical and dielectric properties. On the other hand, the electroactive β-phase content and the degradation temperature of the P(VDF-TrFE-CFE) samples are independent of the processing conditions. At 1 kHz, the highest dielectric constant, ε’ = 40, was obtained for the samples prepared with 15 wt% polymer concentration in solutions and processing conditions based on solvent evaporation and polymer melting at 210 °C. Taking into account the high dielectric response, pressure and bending capacitive sensors were developed with excellent response and high sensibility (0.03 kPa−1). The developed materials were evaluated for bending and force detection applications. Thus, it is concluded that the developed P(VDF-TrFE-CFE) films are suitable for a new generation of multifunctional materials for capacitive sensing applications, including both force and deformation sensors and touchpads.