The effect of thermal loading on negative permittivity in carbon nanofiber/silicone metacomposites

Abstract Nanofiller/polymer composites have recently received much attention for their potential as metacomposites. To date, however, work has focused on understanding the relation between manufacturing parameters and negative permittivity rather than achieving in-operation adaptability. Therefore, this work explores the effect of thermal loading on the negative permittivity of carbon nanofiber (CNF)/silicone nanocomposites as a means to actively change the permittivity of post-manufactured metacomposites. It was found that even modest temperature increases markedly affect the magnitude of negative permittivity, the shape of the permittivity-frequency curve, and the frequency at which permittivity transitions into the negative regime. Further, elevated temperatures and higher CNF concentrations cause the permittivity-frequency response to transition from Lorentz-oscillator to Drude model behavior thereby suggesting a temperature and/or CNF content-initiated change in transport mechanisms. These results are a promising first step towards the realization of on-demand control and adaptability of negative permittivity in next-generation polymeric metacomposites.