Poly(vinyl alcohol)/MXene biomimetic aerogels with tunable mechanical properties and electromagnetic interference shielding performance controlled by pore structure

Abstract

Lightweight biomimetic aerogels with absorption-dominated electromagnetic interference (EMI) shielding have shown greater potential than traditional reflection-dominated metal shields in both civilian and military applications. However, the influence of morphology parameters on the performance of biomimetic aerogels remains significantly unexplored. In this work, Poly(vinyl alcohol) (PVA) assisted transition metal carbides (MXene) aerogels with cellular morphology were fabricated by unidirectional freezing method. The pore channel size/wall thickness was tailored via modulating freezing temperature. Interestingly, the EMI shielding ability improves and the compressible strength declines with increasing the pore channel size/wall thickness. For EMI shielding ability, there should be a saturation of pores-induced multiple reflections and scattering. Therefore, the wall thickness-dominant absorption turns into the decisive factor. In regard of mechanical properties, the deterioration in compressible strength can be attributed to the enhanced stress concentration and the looser stacking of the PVA and MXene. Ultimately, the lightweight PVA/MXene composite aerogels (~33 mg cm−3) can reach the compressible strength at 60% strain of 127.3 kPa and the EMI shielding effectiveness of 40.6 dB based on the freezing temperatures while the volume content of MXene is merely 0.58%.