Significantly Enhanced Dielectric Performance of Poly(vinylidene fluoride-co-hexafluoropylene)-based Composites Filled with Hierarchical Flower-like TiO2 Particles

In this study, we report a feasible strategy for fabricating high-dielectric-constant polymer composites for applications in energy storage devices and embedded capacitors. Hierarchical flower-like TiO2 particles were prepared via a facile solvothermal process and incorporated into the P(VDF-HFP) matrix. The temperature and frequency dependent dielectric properties of flower-like TiO2/P(VDF-HFP) composites as well as commercial TiO2/P(VDF-HFP) composites were investigated. The results reveal that the flower-like TiO2 particles are more effective in increasing the dielectric constant of P(VDF-HFP) when compared with commercial TiO2. Typically, the dielectric constant of the P(VDF-HFP) composite filled with 20 vol % flower-like TiO2 reaches 83.1 at 100 Hz, in contrast to 43.4 for the composite filled with 20 vol % commercial TiO2 and 11.3 for pristine P(VDF-HFP). Also, the flower-like TiO2-filled composites exhibit similar characteristic breakdown strengths to their commercial TiO2-filled counterparts. The significant improvement in the dielectric constant could be attributed to the enhancement of Maxwell-Wagner-Sillars polarization, which originates from the sophisticated morphology of flower-like TiO2 particles.