Improved electrical properties in three phase poly (vinylidene fluoride) nanocomposites with hybrid fillers of titanium dioxide and MXene

High permittivity is attained in nonconducting filled polymer nanocomposites however, overload and agglomeration of nanoparticles typically lead to significantly impaired insulation and dielectric strength properties. Here, 2D Ti3C2 MXene nanosheets without functionalities with a low filler content were incorporated to build three-phase TiO2/MXene/polymer nanocomposites by solution cast method, achieving large dielectric constant and dielectric breakdown strength simultaneously. By substituting small-content conductive MXene for high-concentration TiO2, the permittivity of ternary composites could be increased substantially, which is ascribed to noticeably extended interface interaction. When compared to two-phase TiO2/PVDF composite films, three-phase composites would show somewhat superior loss tangent and ac conductivity because of properly established increased interfacial suitability and filler distribution. A three-phase composite had a dielectric constant of 18.45 and a loss tangent of 0.05 at 1 kHz with fillers of 10 wt% TiO2 and 2 wt% MXene. The maximum dielectric strength of 239.75 MV/m is obtained with 1 wt% TiO2 and 2 wt% MXene in three-phase composites. The permittivity characteristics of PVDF composites with TiO2 and MXene fillers were enhanced by minimizing the synergistic effects between the charge transfer performance of phase conductivity and the charge storage performance of phase ferroelectricity. For nanocomposites comprising 3 wt% of TiO2 and 4 wt% of MXene, the best dielectric permittivity and dielectric loss characteristics (30.2 and 0.037 at 1 kHz, respectively) were found. Furthermore, DC electric field distribution and polarization distribution of composites demonstrated utilizing COMSOL Multiphysics' finite element modeling (FEM) for breakdown strength analysis, results show that good agreement of experimental results. This research may lead the way for the fabrication of promising dielectric composites for utilization in electronics applications.