Efficient Isolation and Solubilization of Pristine Single-Walled Nanotubes in Bile Salt Micelles

We have investigated a wide variety of surfactants for their efficiency in dissolving isolated single‐walled carbon nanotubes (SWNTs) in water. In doing so, we have completely avoided the harsh chemical or mechanical conditions, such as acid or ultrasonic treatments, that are known to damage SWNTs. Bile salts in particular are found to be exceptionally effective in dissolving individual tubes, as evidenced by highly resolved optical absorption spectra, bright bandgap fluorescence, and the unprecedented resolution (∼ 2.5 cm–1) of the radial breathing modes in Raman spectra. This is attributed to the formation of very regular and stable micelles around the nanotubes providing an unusually homogeneous environment. Quantitative information concerning the degree of solubilization is obtained from absorption spectroscopy. A wide range of surfactants are investigated for solubilizing individual intact single‐walled nanotubes –without chemical or ultrasonic treatment. Bile salts are found to be exceptionally effective, and their ordered micelles provide an unusually homogeneous environment for the tubes. This results in highly resolved optical absorption spectra, bright bandgap fluorescence, and unprecedented resolution (∼2.5 cm–1) of the radial breathing modes in Raman spectra (see Figure).