Approaching Technological Limit for Wet‐Pulling Technique

Carbon nanotube fibers (CNTFs) are a promising economical replacement material for contemporary metallic wired conductors due to their lightweight and advanced electromechanical properties. The wet‐pulling technique for CNTF manufacturing is highly versatile, adaptable for both laboratory as well as industrial‐scale production, and can be optimized for the maximum enhancement of electrophysical properties. Herein, a mechanosolvent‐based postfabrication approach for maximizing densification and improving electrical properties of wet‐pulled CNTFs is examined. The experimental process results in fibers achieving 60% of the theoretically maximum density and conductivity of maximally densified metallic single‐walled carbon nanotube bundles. The technique allows a corresponding increase of ≈700% in fiber density (from 100 to 704 kg m⁻³), a simultaneous ≈530% increase in electrical conductivity (from 748 to 3990 S cm⁻¹), and reduced volume defects from 18% to 2%. The approach was combined with a step‐wise microstructure monitoring using focused ion beam–scanning electron microscopy to determine the mechanisms behind the optimized structures. This work is the first to provide an experimental and theoretical base for the postfabrication optimization of wet‐pulled CNTFs and lays the foundation for further enhancement with techniques such as chemical doping, fiber compounding, and combined infiltration/densification mechanisms.