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Lightweight polymer-based nanostructured aerogels are crucial for electromagnetic interference (EMI) shielding to protect electronic devices and humans from electromagnetic radiation. The construction of three-dimensional (3D) conductive networks is crucial to realize the excellent electromagnetic shielding performance of polymer-based aerogels. However, it is difficult to realize the interconnection of different conductive fillers in the polymer matrix, which limits the further improvement of their performance. Herein, 3D ordered hierarchical porous Fe3O4-decorated carbon nanotube (Fe3O4@CNT)/MXene/cross-linked aramid nanofiber (c-ANF)/polyimide (PI) aerogels were prepared via a unidirectional freezing strategy. Benefiting from the magnetic loss effect of Fe3O4 magnetic nanoparticles, the conductive and dielectric loss effects of CNTs, and the multiple reflections induced by the 3D ordered hierarchical porous structure, the Fe3O4@CNTs/MXene/c-ANFs/PI (FMCP) aerogels with the same contents of 8 wt % of Fe3O4@CNTs and MXene exhibit a high absolute EMI shielding effectiveness (SE) of up to 67.42 dB and a microwave reflection (SE R ) of 0.60 dB. More importantly, the phase transition of a small amount of MXene to TiO2 optimizes the impedance matching and transmission and then improves the microwave absorption. The FMCP aerogel has an outstanding normalized surface specific SE (SSE/t) which is up to 62,654 dB cm2·g–1. Meantime, the FMCP aerogels also show super-elasticity and could maintain 91.72% of the maximum stress after 1000 cycles of compression release under a fixed deformation of 60%.

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In this article, we present a facile method for fabricating high thermally conductive and high‐strength polybenzimidazole/boron nitride nanoflakes (BNNS) composites. In brief, based on the method of liquid‐phase exfoliation, the polybenzimidazole functionalized BNNS (f‐BNNS) were facile obtained by directly sonicating the bulk hexagonal boron nitride (h‐BN) flakes/dimethylsulfoxide dispersion in presence of polybenzimidazole. The yield concentration of exfoliated BNNS can facile reach a high concentration of ∼1.43 mg/mL after direct sonication of 10 h with assistance of polybenzimidazole. By means of solution casting, the obtained f‐BNNS/polybenzimidazole composite films shows higher thermally conductivity and mechanical property compared to that of hexagonal boron nitride/polybenzimidazole composites. With 20 wt% of f‐BNNS loading, the yield and ultimate tensile strengths of f‐BNNS/polybenzimidazole composite film can reach ∼225.7 and 252.6 MPa. When the loading of f‐BNNS is 30 wt%, the thermal conductivity of f‐BNNS/polybenzimidazole composites is ∼8.58 W/mK, 27.68 times higher than that of pure polybenzimidazole. POLYM. COMPOS., 39:4285–4297, 2018. © 2017 Society of Plastics Engineers