Fabrication of Highly Dispersed Aramid Nanofibers Based on Cation-Exchange Resin as a Proton Donor: Low Energy Consumption, Solvent Closed-Loop Recovery.

Aramid nanofibers (ANFs), as novel high-performance organic nanomaterials, face challenges in conventional preparation processes where liquid water as a proton donor induces fiber entanglement and cross-linking, leading to poor dispersion stability, while dimethyl sulfoxide (DMSO) solvent remains difficult to recover due to inefficient separation. This study proposes using weakly acidic solid cation-exchange resins as H+ donors instead of water. Their slow-release characteristics effectively inhibit gelation and eliminate mechanical post-treatment. The resulting ANFs exhibit reduced fiber diameters (9.6 ± 1.49 nm) with more uniform size distribution, corresponding to a film tensile strength of 231 MPa, representing 42.07% enhancement compared to traditional water-based methods. Innovatively, the introduction of solid proton donors enables closed-loop DMSO solvent recovery, maintaining a 90% recovery rate after three cycles, significantly reducing production costs. This dual-functional strategy combining fiber structure regulation with green solvent recycling advantages provides new insights for the large-scale production of high-performance nanomaterials.