Dual‐Network Assembled Nanopaper towards Extremely Harsh Conditions

Abstract Aramid nanofibers (ANFs) exhibit desirable lightweight and excellent properties, while their strength has to be sacrificed to further improve their electrical insulation and fire resistance so as to meet the special demands of extreme environments. Herein, Zylon nanofibers (ZNFs) with analogous structure compatibility but superior performance are employed to construct an assembled dual‐network structure to improve the overall properties of ANFs. A facile in situ structure restoration (ISSR) strategy is proposed to achieve ZNF aqueous dispersion for the first time by deprotonation of ZNFs, which significantly avoids the corrosive acid system and facilitates the papermaking process. The composite ANF@ZNF nanopaper exhibits incredible tensile strength (233 MPa) and toughness (14.7 MJ m⁻³), increased by 108% and 584% compared with pure ANF nanopaper due to the dense entangled dual‐network and tremendous hydrogen bonds. Moreover, it presents superior breakdown strength of ≈128 kV mm⁻¹, which is 6 times higher than that of commercial Nomex T410 insulation paper with a thickness of 50 µm. Besides, it exhibits surprising flame resistance (endure 1000 °C burning) ascribed to the excellent thermostability of ZNFs. This work provides promising possibilities for expanding the applications of aramid‐based composites for advanced electrical insulation and thermal protection in extremely harsh conditions.