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

• Published in: Polymer (Guilford) 2021-02, Vol.214, p.123349, Article 123349
• Main Authors: Pereira, N., Gonçalves, S., Barbosa, J.C., Gonçalves, R., Tubio, C.R., Vilas-Vilela, J.L., Costa, C.M., Lanceros-Mendez, S.
• Format: Article
• Language: English
• Subjects: Bending sensors; Beta phase; Capacitive sensors; Chemical properties; Degree of crystallinity; Dielectric constant; Dielectric properties; Electrical properties; Evaporation; Fluorides; Fluorinated polymers; Morphology; Multifunctional materials; Permittivity; Polymers; Sensors; Solvent casting; Solvents; Temperature; Touch control panels; Vinylidene; Vinylidene fluoride
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2020.123349

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. [Display omitted] •Poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) has been processed by solvent casting.•Varying processing conditions include polymer concentration in solution and processing temperature.•A high dielectric constant of 40 at 1 kHz has been obtained.•The material shows high performance for capacitive pressure and bending sensor applications.