Hygrothermal aging behavior of sandwich-structure Ba_0.6Sr_0.4TiO₃/PVDF composites with high energy storage property and dielectric tunability

Ba_0.6Sr_0.4TiO₃/PVDF composite is a promising material to be applied to manufacture filters, phase shifters, biosensors, and other electronic components due to its excellent dielectric constant, dielectric tunability and good biocompatibility. However, as a polymer material, the PVDF matrix will have a series of aging behaviors during the actual use, which will affect the stability and service life of components. In this work, two sandwich structure BST/PVDF composites with different ceramic morphologies (namely 0D-BPB and 2D-BPB) were prepared, and the effects of hygrothermal aging times on the chemical structure, energy storage properties, and dielectric tunability of the composites were studied. The results show that the physical properties of both 0D-BPB and 2D-BPB will deteriorate with increasing aging time under hygrothermal conditions, which resulted from the PVDF phase transition from β to γ phase. And the 2D-BPB sandwich structure composite has the best anti-hygrothermal aging behavior. When the hygrothermal aging time is 480 h, which is approximately equal to the actual natural environment for 7 years, the energy storage and dielectric properties are still showed a high level: the dielectric constant of 2D-BPB is 27.6, the energy storage density is 12.64 J/cm³, and the dielectric tunability is 78.4 %, respectively. The results provide certain reliability for the application of BST/PVDF in various electronic components.