Dual‐Polymer‐Assisted Dry‐Jet Acid Spinning of Ultra‐Low‐Aspect‐Ratio Multiwalled Carbon Nanotubes Into Continuous Load‐Bearing Fibers

The assembly of low‐cost, mass‐produced yet “low‐quality” multiwalled carbon nanotubes (MWCNTs) into robust, load‐bearing fibers remains a significant challenge due to their low aspect ratio, poor dispersibility, high impurity content, and difficulty in achieving alignment. Here, we report a synergistic dual‐polymer‐assisted dry‐jet acid spinning (DPA‐DJAS) strategy for directly converting powder‐like MWCNTs with an ultra‐low aspect ratio of only 58–375 into continuous, high‐performance fibers. Inside the dope, an acid‐soluble poly(p‐phenylene terephthalamide) enables uniform MWCNT dispersion and optimizes spinning dope rheology for continuous extrusion. Across the air gap, the dry jet promotes gravitational drawing, surface pregelation, and improved MWCNT alignment. In the coagulation bath, polyvinyl alcohol in the coagulation bath moderates the H ₂ SO ₄ –H ₂ O exchange, yielding strip‐like oriented surfaces and densely stacked MWCNTs. The resulting fibers exhibit exceptional mechanical performance, achieving tensile strengths exceeding 150 MPa and elongations up to 6.35%, while maintaining a low initial Young's modulus of ≈50 MPa—only 1.8% of that in conventionally spun CNT fibers but with a 2.57‐fold increase in strength. Remarkably, a representative fiber with linear density of ≈43.8 tex can sustain a 100 g handling load via direct knotting, corresponding to an apparent tenacity of ≈2.24 cN/tex. In addition, electrical conductivity is significantly enhanced, reaching 551 S m ⁻¹ —an increase of 124% over conventional acid‐spun CNT fibers. This DPA‐DJAS method eliminates the need for “high‐quality” CNT feedstocks and provides a scalable route to process industrial‐grade MWCNT powders into lightweight, flexible, and conductive fibers for next‐generation smart textiles, flexible electronics, and structural applications.