Liquid-crystalline behaviors of single-walled carbon nanotube aqueous dispersions with different nanotube aspect ratios and surfactants

We investigate the liquid crystal (LC) phase behaviors of the sodium cholate stabilized single-walled carbon nanotube (SWCNT) aqueous dispersions with different SWCNT aspect ratios. The isotropic-to-nematic phase transition occurs at a lower concentration for the SWCNT dispersion with a larger aspect ratio, which is expected by the Onsager theory. The well-aligned film is successfully fabricated from the dispersion with the higher SWCNT aspect ratio by the simple blade coating. We also prepare the SWCNT dispersions with different surfactants, sodium deoxycholate, and sodium taurodeoxycholate, changing the surface condition of SWCNTs, which may affect the LC transition concentrations.