Reversible dispersion and precipitation of single-walled carbon nanotubes using a pH-responsive rigid surfactant.

A pH-responsive rigid surfactant derived from rosin was used to disperse and precipitate single-walled carbon nanotubes (SWNTs) in aqueous solution. The precipitated SWNTs could be re-dispersed by changing the pH without sonication owing to the hydrophobic steric layers formed by the rigid group and π-π interactions from the azobenzene group.