Enhanced dielectric properties of ferroelectric polymer composites by surface-modified BaTiO₃ particles

Barium titanate (BaTiO3, BT)/poly (vinylidene fluoride, PVDF) composites containing 0%-50% of ceramic filler volume fraction were fabricated by spin-coating method, and it was shown that the permittivity of BT/PVDF composites increased with the addition of ceramic filler. In order to enhance the interfacial bonding between the two phases, the surface modification treatment of BT ceramic particles was carried out using different mass fractions of gamma-Aminopropyl-triethoxysilane (KH550). The results indicated that the dielectric properties of the modified composites were enhanced. The dielectric constant of the BT/PVDF composite with 10 vol.% ceramic filler treated with 1 wt.% KH550 is 20.3, which is twice as much as pure PVDF. A model of BT/PVDF dielectric composite was employed by using COMSOL Multiphysics to simulate and analyze the effects of filler particle size, volume fraction, and degree of dispersion on the properties of composite dielectric films from the perspective of microstructural. Calculated results show that the addition of ceramic particles triggers local electric field distortion, which affects the dielectric properties of the composites. Meanwhile, the degree of dispersion of the filler also affects the breakdown resistance of the composite material, when the filler is uniformly dispersed, the local electric field is reduced, which effectively enhances the breakdown resistance of the material. Finite element simulation analyzes the macroscopic dielectric properties from a microstructural point of view, which is beneficial for further understanding of ceramic-polymer composites.