Scalable Fabrication of Anisotropic Heterocyclic Aramid Nanofiber Films with Ultrahigh Toughness for Insulation and Thermal Management Applications

One-dimensional (1D) heterocyclic aramid nanofiber (HANF)-based films have garnered significant research interest due to their excellent mechanical, insulative, and high temperature resistance performances. In this study, we developed an innovative sol–gel transition strategy for fabricating continuous HANF films with highly aligned nanostructures and pronounced mechanical anisotropy via blade-coating. A bottom-up strategy of low-temperature solution polycondensation was used for the synthesis of polymeric precursors, which were self-assembled into nanofibers through hydrogen-bonding-induced aggregation. Notably, methoxy poly(ethylene glycol) (mPEG) was incorporated into the poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) polymerization to modulate the self-assembly process. The resulting mPBIA nanofiber film demonstrated remarkable anisotropic behavior, which exhibited a tensile strength of 184 MPa with divergent rupture strains of 5.4% (parallel to coating direction), 33.2% (45°), and 50.6% (perpendicular) relative to the blade-coating orientation. Post-hot-pressing treatment, the mPBIA film achieved an impressive dielectric breakdown strength of 169.4 kV mm–1, coupled with exceptional thermal stability and efficient heat dissipation capability. This scalable manufacturing approach establishes HANF films as a promising platform for developing advanced composite materials with tailored functionalities.