Manipulation of PMMA/PVDF-based nanocomposites by heat treatment resulted in significantly enhanced energy density

PVDF is one of the most researched polymers for the development of high energy density film capacitors, and its crystalline structure and dipole motion are closely related to the energy density. In this work, the low-loss amorphous polymer PMMA was introduced as a reinforcing phase to blend with PVDF to form a matrix. PMMA/PVDF-BT nanocomposites were prepared by spin-coating method and subjected to quenching heat treatment in three media, namely, deionized water, ice water, and liquid nitrogen, respectively. The results showed that the quenching heat treatment achieved a synergistic increase in permittivity and breakdown strength without sacrificing the mechanical properties of the nanocomposites, while maintaining a low dielectric loss. The discharge energy density of the quenched heat-treated PMMA/PVDF-BT nanocomposite in ice water at 180 °C was 11.5 J/cm 3 (3100 kV/cm), which was about 958.33 % of the best commercial BOPP film (1.2 J/cm 3 ). This work has great potential as flexible dielectric substrates for advanced and sophisticated film capacitors.