Negative permittivity of polyimide-based percolative composites with zero/one dimensional functional fillers

The construction of conductor/insulator composites based on percolation theory is a hot method for achieving negative permittivity in the radio frequency range. The morphology of functional fillers strongly affects the electron transport behavior and the performance of negative permittivity. However, research on the influence between the morphology of the functional fillers and negative permittivity seems to have been overlooked in the past. In this work, different contents of acetylene black/polyimide (ACET/PI) and multiwalled carbon nanotubes/polyimide (MWCNTs/PI) composites were successfully prepared to reveal the relationship between the morphology of the functional fillers, performance of negative permittivity, and the electron transport behavior. The difference in morphology of fillers directly affects the formation of conductive networks and the numerical value of percolation threshold, ultimately affecting the characteristics of negative permittivity. Moreover, the Drude model is used to analyze the negative permittivity behavior of composites with different conductive fillers. Research on impedance indicates that materials with negative permittivity exhibit inductive characteristics. This work provides a basis for the selection of functional fillers and performance control of materials with negative permittivity.