Hierarchical-structured dielectric permittivity and breakdown performances of polymer-ceramic nanocomposites

Polymer-ceramic nanocomposites with high dielectric permittivity, breakdown strength and energy storage density are of urgent demand in advanced electronics industry. The interface between polymer matrix and ceramic fillers plays an essential role in dielectric performances of nanocomposite due to the interfacial polarization. In this contribution, four types nanocomposites with different hierarchical structures, namely poly(vinylidene fluoride) (PVDF) with BaTiO3 nanofibers(BT_nfs), TiO2 nanofibers (TO_nfs), BT nanoparticles inside TO nanofibers (TO_nfs@BT_nps in short), BT nanofibers inside TO nanofibers (TO_nfs@BT_nfs in short) are proposed. The dielectric permittivity and breakdown strength are respectively calculated through a finite element method and a phase field method. Results indicate that as the volume fraction of ceramic increases, the dielectric permittivity raises while the breakdown strength decreases. Nanocomposites with BT_nfs show the highest dielectric permittivity but lowest breakdown strength. Meanwhile nanocomposites with TO_nfs perform exactly the opposite way. Nanocomposites with TO_nfs@BT_nfs demonstrate both high dielectric permittivity and breakdown strength.