Two-step re-protonation strategy to fabricate aramid nanofiber sheet (ANFS) based high performance composite film

Aramid nanofibers have aroused great research enthusiasm in functional composites thanks to their numerous advantages. However, the mechanism of proton recovery in aramid nanofibers regeneration is still unclear, and the mechanical properties of aramid nanofibers, which simply and roughly regenerated from water in one-step, are still insufficient. In this work, we explore the mechanism of aramid nanofiber proton reconstruction by eight proton donor ability solvents and prepared a macroscopic sheet-like aramid nanofiber (ANFS). Studies show that weak proton donor is more likely to recover intermolecular -H-bonds, and strong proton donor is more likely to recover intramolecular -H-bonds in aramid nanofibers. Based on above, we proposed a two-step re-protonation strategy (EG + H2O) to recover aramid nanofibers structure to obtain high performance ANFS film. Furthermore, high efficiency thermal transfer channel constructed by aligned BN nanosheets along with ANFS lamellae configuration facilitate high thermal conductivity (in-plane) of 19.66 W m−1 K−1 with surprising mechanical properties with 211 MPa tensile strength, 12.8 % elongation at break, toughness of 17.94 MJ/m3 and only 10 wt% filler. This work provides a novel insight for aramid nanofibers re-protonation and high efficiency heat transfer path to obtain mechanically strong and highly thermal conductive composites.