Multiple light scattering measurement and stability analysis of aqueous carbon nanotube dispersions

In this study, surfactants were selected for the process of dispersing carbon nanotubes (CNTs) in water, in order to minimize the impact of the chemical modification of the individual CNTs on their inherent properties. The CNTs were sonicated in aqueous solutions of the various surfactants, viz. the anionic sodium dodecylbenzene sulfonate, the cationic cetyl trimethylammonium bromide, and the non-ionic Triton X-100, in order to stabilize the CNTs against the van der Waals attractive forces. The concentration of each surfactant was approximately 0.3 wt% and the concentration of CNTs used for their homogeneous dispersions in aqueous solution was 0.02 wt%. Furthermore, the stabilizing abilities of the aqueous CNT dispersions were measured using a recently developed optical analyzer (Turbiscan). This study shows that the surfactants successfully stabilized the aqueous CNT dispersions, whereas in the absence of surfactants they rapidly sedimented.