Towards inhibiting conductivity of Mo/PVDF composites through building MoO3 shell as an interlayer for enhanced dielectric properties

Polymer dielectrics have received increasing attention owing to their wide applications in electrical, microelectronic and energy storage fields. However, it remains a challenging to prepare polymer dielectrics with a high dielectric constant (epsilon) but low dissipation factor (tan delta). In this work, conductive molybdenum (Mo) particles were encapsulated by a thin layer of semi-conductive molybdenum trioxide (MoO3) with a wide bandgap of 3.28 eV via a facile thermal calcination way under air, and the gained core-shell structured Mo@MoO3 particles were composited with poly(vinylidene fluoride) (PVDF) to generate morphology-controllable high-epsilon but low loss composites. The large epsilon can be realized in the PVDF composites with the Mo@MoO3, and both the electric conductivity and tan delta of the composites are significantly restrained to rather low levels even at high filler loadings, and apparently decrease with increasing the MoO3' shell thickness. The significantly ameliorated dielectric performances can be ascribed to the presence of MoO3 interlayer preventing the Mo particles from direct contact with each other and simultaneously hindering the long-range electron migration. The developed Mo@MoO3/PVDF composites with a high epsilon but low loss are great potential applications for electrical industries and microelectronic industries.

Automated summary

Polymer dielectrics with high dielectric constant (epsilon) but low dissipation factor (tan delta) are challenging to prepare. In this work, conductive molybdenum particles were encapsulated with a thin layer of semiconductive molybdenum trioxide to form core-shell structured particles. These particles were then composited with poly(vinylidene fluoride) to generate morphology-controllable composites with high epsilon and low loss. The presence of the molybdenum trioxide interlayer prevents direct contact between particles and hinders long-range electron migration, leading to significantly improved dielectric performances.