Weakly negative permittivity with frequency-independent behavior in flexible thermoplastic polyurethanes/multi-walled carbon nanotubes metacomposites

Abstract Negative permittivity has been attracted tremendous interests because of its excellent advantages and great contributions to developing metamaterials. In this paper, the permittivity and electrical conductivity are presented in thermoplastic polyurethanes/multi-walled carbon nanotubes (TPU/MWCNTs) composites. Small absolute values of negative permittivity and good frequency stability are achieved by selectively adding different content of MWCNTs into TPU matrix, which is possible for potential applications in different fields such as organic vapor sensing, electromagnetic interference shielding and wearable electronic devices. Meanwhile, a feasible way of tunable negative permittivity is also acquired.