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.