▎ 摘　　要

Aramid nanofibers (ANFs) are promising polymeric nanoscale building block as matrix for high-strength composites, but remain to be explored fully. In this work, we demonstrate a hydrogel processing route to fabricate ultrastrong ANF-based nanocomposite film. A uniform mixed dispersion containing ANF and branched poly (ethylenimine)-modified graphene oxide (BGO) is converted into hydrogel, followed by chemical crosslinking and pre-stretching treatment. This unique hydrogel processing route allows step-by-step optimization of BGO loading, interfacial crosslinking and ANF orientation, and thus leads to well-organized ANF-based nanocomposite film. The nanocomposite film shows a tensile strength of similar to 616 MPa and a Young's modulus of similar to 33 GPa, which are 4 and 15 times higher than those of pure ANF film and superior to all reported ANF-based nanocomposites. Experimental characterizations suggest that the superb mechanical property is benefited from uniform dispersion of BGO, multiple hydrogen bonding between BGO and ANF, alignment of ANF matrix and covalent crosslinking between BGO nanosheets. Our study provides innovative insights into the fabrication of ultrastrong ANF-based nanocomposites and is potentially extendable to their nanocomposites reinforced with other nanoscale fillers.