Tailoring dielectric properties of polymer matrix composites for high-performance flexible sensors

Abstract

Polymer matrix composites with high dielectric constants and low dielectric losses are in high demand for flexible electronics. However, simultaneously satisfying these requirements poses a significant scientific challenge owing to the intrinsic trade-off relationship. Herein, we utilized the in situ controllable reduction of graphene oxide (GO) within a poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) matrix to regulate the dielectric properties. The as-obtained composite exhibited a high relative dielectric constant of 1415 coupled with a low loss tangent of 0.380 at 100 Hz. Experimental and theoretical studies indicate that the increased degree of electron conjugation and conductivity of the reduced GO (RGO) are responsible for the high-k. The constrained reduction degree of GO, combined with its homogeneous dispersion in the polymer matrix, effectively suppresses long-range charge carrier migration, thereby minimizing dielectric loss. This novel strategy could be successfully applied to both organic and aqueous systems. Furthermore, a high-performance flexible capacitive proximity sensor was exemplified by the optimization of both the dielectric layer and electrode pattern, exhibiting excellent sensitivity and stability. The fundamental mechanisms elucidated in this study provide crucial design principles for developing dielectric PMCs with tailored properties, thereby opening new avenues for advanced flexible electronic applications.