Steric stabilizer-based promotion of uniform polyaniline shell for enhanced electromagnetic wave absorption of carbon nanotube/polyaniline hybrids

Carbon nanotubes (CNTs) are potential electromagnetic (EM) wave absorption (MA) material due to the strong dielectric loss, nevertheless, sole CNTs suffer from limited MA ability because of the interface impedance mismatch of CNTs and the skin effect, which leads to high reflection of EM wave. The impedance mismatch characteristics of CNTs can be effectively improved by incorporation of polyaniline (PANI) with an intermediate conductivity. However, to optimize the dispersion of CNTs and incorporate PANI into CNTs uniformly, chemical modifications were generally utilized. These methods involve strong acid and thus suffers from long-term and high risk. In particular, these methods would destroy the conjugate structure of CNTs and thus deteriorate the dielectric loss. Herein, the introducing of polyvinyl pyrrolidone (PVP) not only improves the dispersion of CNTs, but also helps to produce the monomer micelle and uniformly self-assemble on the surface of CNTs as steric stabilizer. The uniform PANI shell can solve the contradiction between strong dielectric loss of CNTs and the poor property of impedance match between CNTs and air, resulting in excellent MA ability. The minimum reflection loss (RLmin) of obtained CNT/PANI hybrid reaches -41.5 dB at 9.5 GHz when the absorber mass ratio was only 10% due to the good dispersion of CNT/PANI hybrids. The effective absorption bandwidth (EB) with RL <= -10 dB reaches 5.1 GHz at the thicknesses of 2 mm. This work provides a facile, eco-friendly and defect-free way to fabricate CNT/PANI hybrid with excellent and tunable performance of MA.