Thermal behavior of the dielectric response of composites based on poly(vinylidene fluoride) filled with two-dimensional V2CTx MXenes

Abstract

In this study, two-dimensional V₂CT_x MXenes were prepared by an accessible and rapid method, which involved aluminothermic combustion synthesis of the V₂AlC MAX phase and its further processing in an HCl/LiF mixture under hydrothermal conditions. The resulting V₂CT_x MXene was characterised by XRD, SEM, TEM and XANES. A colloidal solution of the V₂CT_x MXene in dimethylformamide was used to prepare nanocomposites based on a poly(vinylidene fluoride) polymer matrix with a conductive filler content of 2.5 to 20 wt%. The nanocomposites were characterised by XRD, SEM and simultaneous DSC-TG analysis. The dielectric properties of the nanocomposites were studied using impedance spectroscopy in the frequency range from 100 Hz to 1 MHz at temperatures from −50 to +140 °C. The results showed that adding 20 wt% V₂CT_x to PVDF allows increasing the permittivity to 425.3 with a dielectric loss tangent of 0.54 at a frequency of 10 kHz. Studies of the temperature behavior of the dielectric response of composites have shown that the nature of the temperature dependence of the permittivity and dielectric loss tangent was determined mainly by the characteristics of the PVDF polymer matrix, while the filler had a significant effect only on the interfacial polarization, which increased with increasing V₂CT_x filler concentration and temperature.