Preparation and characterization of flexible, free‐standing, and easy‐fabricating BaTiO₃‐P(VDF‐CTFE) dielectric nanocomposite

Abstract The flexible and free‐standing nanocomposite films were fabricated by a simple solution‐casting process using BaTiO₃ nanoparticles as fillers and P(VDF‐CTFE) 91/9 mol% as polymer matrix. To obtain good wettability between ceramic and polymer, the coupling agent 3‐Aminopropyltriethoxysilane was used to modify the surface of BaTiO₃ fillers. A good compatibility of BaTiO₃ and P(VDF‐CTFE) was achieved when a small amount of coupling agent was used for the surface modification of BaTiO₃ fillers; therefore, the nanocomposites with a dense and uniform microstructure was obtained. It was experimentally found that both dielectric constant and breakdown strength were increased with a suitable amount of coupling agent due to the good compatibility. A dielectric constant of 51 at 1 kHz was obtained with 30 vol% fillers and 2 wt% coupling agent, which was about four times of that for the pure P(VDF‐CTFE) film. When an appropriate amount of coupling agent was coated on fillers, the energy storage density of the composite system was improved. A maximal discharge energy‐storage density of 3.8 J/cm³ was obtained for the nanocomposite film with 5 vol% of BaTiO₃ and 2 wt% coupling agent, which is much higher than that of the composites without coupling agent.