Towards Solutions of Single-Walled Carbon Nanotubes in Common Solvents

Spontaneous exfoliation of single‐walled carbon nanotubes on dilution of dispersions in a common solvent, N‐methyl‐pyrrolidone, is demonstrated. The free‐energy of mixing is negative, confirming athermal solubility. Scanning tunneling microscopy measurements show physisorption of the solvent to the nanotube (see figure). Experiments, supported by a simple model, show that successful solvents for nanotubes are those with surface tensions close to that of graphite.