Surfactant-Assisting Stable Dispersion of Carbon Nanotubes in Room-Temperature Ionic Liquids

Carbon nanotubes (CNTs) were stably dispersed in the earliest studied room-temperature ionic liquid, ethylammonium nitrate (EAN), using nonionic surfactants (Tween-20, Tween-60 and Tween-80) as dispersants. The stably dispersed CNTs in ionic liquid can not coagulate even after centrifugation at high speed. Nonionic surfactant micelles in EAN could play an important role for the stably dispersed CNTs, which were determined by surface tension measurements. Spectroscopy measurements and electronic microscopy observations were used to study the stably dispersed samples. The Raman spectra show characteristic Raman bands of CNTs dispersed in EAN. UV-vis-NIR absorption spectra exhibit the strong adsorption peaks of single-wall carbon nanotubes. Transmission electronic microscopy (TEM) images indicate the CNTs are exfoliated to form individual tubes in ionic liquids.