Single-Walled Carbon Nanotube Dispersant for the Controlled Assembly into Conductive Films, Aligned Films, and Fibers

Abstract

The practical deployment of single-walled carbon nanotubes (SWCNTs) in advanced devices relies heavily on their solution processability. However, dispersion remains a significant challenge due to competing requirements: effective exfoliation demands strong energy input, which often leads to structural damage, and dispersant selection depends on solvent compatibility, target concentration, and intended application. Here, we report the design and synthesis of a highly versatile azobenzene-based dispersant (AB) that addresses these limitations by enabling the dispersion of SWCNTs with minimal damage in both aqueous and polar organic solvents. The AB dispersant promotes partial isolation of ultralong SWCNTs, up to tens of micrometers in length, while reducing the rest into small bundles of only a few tubes with well-preserved crystallinity. To demonstrate the broad utility of this dispersant, we applied AB-dispersed SWCNTs to three distinct device-relevant applications: transparent conductive films (TCFs), aligned coatings, and conductive fibers. The TCFs fabricated from aqueous AB dispersions exhibited high transmittance (88 and 76%) and low sheet resistance (86 and 67 Ω/sq) without postdeposition doping, surpassing most CNT–TCFs prepared by wet-coating methods. Aligned SWCNT films were formed via shear-assisted coating with a nematic order parameter of S_2D = 0.33. Fully aqueous wet spinning into calcium acetate solutions yielded dense (1.1 g/cm³), highly conductive (5932 S/cm) fibers. Our results demonstrate that the AB dispersant provides a unified and scalable strategy for producing high-performance CNT materials with minimal structural degradation. While further optimization of the processes for the individual application is necessary to improve alignment, density, and mechanical properties, these results represent a critical step toward application-flexible, sustainable, and industrially viable CNT processing.