Investigation into elevated dielectric properties of molybdenum particle /PVDF composites by engineering insulating silica shell as an interlayer

The urgent requirement for high reliability and increasingly miniaturized electronic devices necessitates packaging polymers with giant dielectric constant (ε′), low loss and high breakdown strength (Eb). To significantly restrain the dielectric loss and leakage current of molybdenum (Mo)/poly (vinylidene fluoride, PVDF) while still holding a large ε′, the silica (SiO2) encapsulated Mo core@shell structured particles were prepared in this work utilizing a sol-gel method, and then composited with PVDF to explore the silica shell's impact and regulating effect on the dielectric properties of the PVDF composites. The findings on the relationship between microstructure and dielectric properties showcase that the introduced SiO2 interlayer not only enhances the interface interactions but also mitigates the great interfacial mismatch in both ε′ and conductivity between the two components, resulting in elevated Eb of the composites. Moreover, the dielectric loss and conductivity of the composites can be remarkably reduced because the silica shell introduces deep traps inhibiting the passage of long-distance electron migration. And the overall dielectric properties of the Mo@SiO2/PVDF can be effectively tuned by modifying the Mo@SiO2's electric resistivity and optimizing the shell thickness. This work provides a beneficial strategy for the design and preparation of dielectric composites with superior dielectric performances for prospective applications. •The Mo@SiO2/PVDF exhibits superior overall dielectric properties than pure Mo/PVDF.•The SiO2 layer mitigates the mismatch in ε′ and conductivity between filler and matrix, elevating Eb of the composites.•The SiO2 shell introduces deep traps, inhibits electron migration resulting in very low dielectric loss.•The dielectric properties of the Mo@SiO2/PVDF can be modulated via adjusting the silica thickness.