Anisotropic electromagnetic wave absorption performance of Polyimide/multi-walled carbon nanotubes composite aerogels with aligned slit-like channels structure

Abstract

Polyimide/carboxyl functionalized multi-walled carbon nanotubes (PI/MWCNTs-COOH) composite aerogels with aligned slit-like channels structure were synthesized through unidirectional freezing, freeze-drying and thermal imidization process in sequence. The composite aerogels with high porosity and low density exhibited highly aligned slit-like channels structure, which further imparted anisotropic electrical conductivity, electromagnetic wave absorption, and compression properties to the aerogels. PI/MWCNTs-COOH-16phr composite aerogel showed the minimum reflection loss (RLmin) of −52 dB at 12.8 GHz and effective absorption bandwidth of 6.7 GHz (10.6 ∼ 17.3 GHz) with a thickness of only 2.5 mm in the perpendicular direction to the aligned slit-like channels, while its RLmin was only −11 dB at 15.9 GHz in the orientation direction of slit-like channels. The composite aerogel had prominent thermal stability, with T5% in nitrogen up to 564 °C. The high temperature resistant and lightweight polyimide-based highly efficient EMW absorbing structural material manufactured by this research had great potential for aerospace applications.