Acid-Free Liquid Crystalline Single-Walled Carbon Nanotube Polyelectrolytes for Interconnected Fibers, Yarns, and...

Liquid crystalline (LC) solutions of single-walled carbon nanotubes (SWCNTs) provide an attractive route to ordered fibers, films, and coatings, with exceptional multifunctional properties. Here, the formation of nematic phases, using reductive chemistry, to generate SWCNT polyelectrolytes (sodium nanotubides) as an alternative to routes based on superacids is elucidated. Strikingly, the stable mesophase domain of SWCNT polyelectrolytes extends to spontaneous LC nematic formation at a low concentration of 0.18 mg mL^-1; the isotropic-nematic phase boundary is mapped out and found to relate, through the Debye length, to the effective aspect ratio in accordance with Onsager's theory. These LC SWCNT polyelectrolyte solutions are shown to allow the direct, scalable, and safer processing of macroscopic assemblies such as fibers, yarns, pastes, and textile coatings, which are effective for transmitting electrical signals (electrical conductivity ∼1.0 MS m^-1). These processes are illustrated by a range of electronic textile devices built around SWCNT-coated cotton, connected by SWCNT yarns. Acid-free processing is compatible with a much broader range of equipment, functionalization chemistries, and substrates by providing many opportunities for development.