Enhanced electroactive β‐phase and dielectric properties in P(VDF‐HFP) composite flexible films through doping with three calcium chloride salts: CaCl₂, CaCl₂·2H₂O, and CaCl₂·6H₂O

Abstract

Flexible dielectric films with a high dielectric constant, utilizing P(VDF‐HFP)/salt composites, were manufactured through the solution casting method. In this work, we studied the impacts of three calcium chloride salts—CaCl2, CaCl2·2H2O, and CaCl2·6H2O—on the surface morphology, crystalline phase transformation, mechanical properties, and dielectric responses of the P(VDF‐HFP) copolymer. The detailed structure and properties of all samples were assessed via scanning electron microscope (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), tensile testing, and LCR meter analysis. The experimental results demonstrated that the addition of calcium salts to the P(VDF‐HFP) composites induced a visibly microporous morphology, with the porosity and surface roughness of the composites gradually increasing with salt content. In comparison to the pure P(VDF‐HFP) film, the composite films exhibited decreased stiffness and heightened flexibility. Furthermore, a higher β‐phase fraction and notable enhancements in the dielectric constant resulting from the inclusion of calcium salts were observed. Consequently, the P(VDF‐HFP) composite filled with 3 wt% of CaCl2·6H2O demonstrated the highest capability for promoting the β‐phase fraction and dielectric constant, achieving values of 98.33% and 21.49% (at 10 Hz), respectively.