Interface insight of Mo@PS/PVDF dielectrics towards meliorative dielectric performances via engineering organic PS as an interlayer

Developing polymer dielectrics with a low dielectric loss but high dielectric permittivity ( ε′ ) and breakdown strength ( E b ) is steadily expected for applications in microelectronic and electrical industries. In this study, to elevate the overall dielectric properties of molybdenum (Mo)/poly(vinylidene fluoride) (PVDF), an insulating polystyrene (PS) shell was first constructed on the Mo’s surface through a suspension polymerization, and then the core-shell Mo@PS particles were compounded with the host PVDF. The PS shell’s influence on the dielectric performances of the composites was explored in terms of the filler concentration, diverse shell thicknesses and frequency. Compared with neat Mo/PVDF, the Mo@PS/PVDF composites present immensely restrained loss and conductivity owing to the insulating PS interlayer stopping the physical contact among Mo powder and wonderfully constraining the long-range charges migration. More importantly, the integrated dielectric performances can be efficaciously tuned and optimized via engineering the PS shell’s thickness because the PS shell not only bolsters the interfacial interactions, but also alleviates the local electric field distortion and concentration subsequently leading to boosted E b . Analyzing the dielectric results via the Havriliak-Negami expression theoretically illustrates the underlying polarization mechanism in the composites. The resulting Mo@PS/PVDF composites owing high ε′ and E b coupled with fairly low loss, present prospective applications in electrical power systems.