Layer-by-layer assembled aramid nanofiber/MXene aerogel: Exceptional resistance to extreme temperatures and robust anisotropy for advanced applications

Aerogels are characterized with unique morphology and physical properties, thus are serving as essential elements in advanced applications. Nowadays, the delicate intelligent devices are frequently exposed in harsh environments, leading to multiple issues during application of functional aerogels including the limited resistance to extreme temperatures, requiring encapsulation prior to usage, and accumulation of Joule heat. In this study, we fabricated a multilayered aramid nanofiber (ANF)/MXene aerogel with the layer-by-layer stacking ANF and ANF/MXene layers. Attributing to the multilayered and porous structure, the aerogel displayed proper EMI shielding performance which maintained stable in harsh environments of excessive high temperature (200 degrees C) and low temperature (-196 degrees C). More importantly, obvious anisotropy in electrical conductivity (similar to 8 orders of magnitude) and thermal insulation (Delta T = 32 degrees C) was obtained along the in-plane and out-of-plane directions. As two demonstrations of potential applications, the sensing performance and thermal insulating property of the ANF/MXene aerogel was displayed. Inspiringly, the aerogel sensor exhibited significant durability and notable sensitivity to different deformations. Also, the aerogel displayed rapid heat dissipation along the in-plane direction while efficient thermal insulation along the out-of-plane direction, thus, can be applied in thermal management to protect the electronic devices. Therefore, the as-prepared ANF/MXene aerogel can serve as EMI shielding parts, encapsulation-free flexible electronics as compression sensor and anisotropic thermal insulator, which has great potential in the application of intelligent devices.