Design and preparation of MOF@PDA core-shell particles embedded with nano- Ag for PVDF dielectric composites

Abstract In recent years, dielectric composites as excellent energy storage materials have attracted extensive attention from scholars. Improving the energy storage density of dielectric composites can start from two aspects: increasing the dielectric constant and breakdown field strength of materials. In this paper, the metal-organic framework (MOF) ZIF-67 were selected, the polydopamine (PDA) core shell were coated on the surface of ZIF-67, and nano-Ag were embedded in the PDA, and MOF@PDA-Ag hybrid nanoparticles were prepared. Nanoparticles were introduced into the polyvinylidene fluoride (PVDF) matrix, and MOF@PDA-Ag/PVDF nanocomposites were prepared. The results show that ZIF-67 promote the generation of β-phase in the PVDF matrix, which improve the overall polarization capacity of the composites, thereby improving the mechanical properties and dielectric properties of the materials. Under the strengthening effect of nano-Ag, the dielectric constant of 7 wt% 10MOF@PDA-Ag/PVDF nanocomposite film reaches 15.6 (100 Hz), which is 54.5% higher than that of pure PVDF. Under the influence of the insulation stability of ZIF-67 and PDA and the Coulomb blocking effect of nano-Ag, the breakdown field strength of 5 wt% 10MOF@PDA-Ag/PVDF nanocomposite film is increased to 159kV/mm, which is 62.2% higher than that of pure PVDF.