Enhanced dielectric properties of polyvinylidene difluoride composite films by boron nitride nanosheet @ metal organic framework hybrid fillers

Generally, it is hard to simultaneously achieve the enhanced dielectric constant and breakdown strength of polymeric composite by simply introducing fillers into polymers. In this work, a novel hybrid fillers boron nitride nanosheet @ metal organic framework (BNNS@MOF), in which the nanoscale UiO-66-NH₂ were epitaxially loaded on layer surface of the BNNSs, was prepared by the hydrothermal reaction. The test results indicate that the BNNS@MOF hybrid fillers were endowed with high breakdown resistance of BNNS and high dielectric constant of UiO-66-NH₂. After introducing 1 wt% BNNS@MOF hybrid fillers into polyvinylidene fluoride (PVDF) at the frequency of 10² Hz, PVDF composite films demonstrated a relatively high dielectric constant (ε = 10.7), and energy density (U_e = 6.06 J/cm³) under the high breakdown strength (E_b = 378 MV/m), but low dielectric loss (tan (δ) = 0.039). Compared to PVDF with simply mixed BNNS and UiO-66-NH₂ (ε = 12, tan (δ) = 0.061, U_e = 3.14 J/cm³, E_b = 249 MV/m), hybrid fillers showed significant advantages. Our work presented a new idea to construct the PVDF composites with simultaneously enhanced dielectric constant and breakdown strength by introducing hybrid fillers. The hybrid fillers showed promising application in the field of film capacitors.