Solvent effects on the mechanical properties of aramid nanofibers film

• H 2 O/EtOH as re-protonation solvent can largely enhance the stress of ANFs film. • The enhanced stress is due to the lowered R a and structural densification. • The variation of stress also has some deviations with R a due to other factors. Herein, we revealed that using the mixture of water and ethanol (EtOH) as re-protonation solvent of aramid nanofibers (ANFs) dispersion in dimethyl sulfoxide can largely improve the mechanical strength of subsequently assembled ANFs film, in which the enhancements are strongly related to the Hansen solubility parameters distance ( R a ). The lower R a can yield the denser microstructures, the higher mechanical strength and toughness. This work advanced the strength of ANFs film from 191 MPa to 300 MPa, which provided a novel strategy to prepare high performance ANFs based films and had potential to be used as aerospace material.