Single-wall carbon nanotubes (SWCNTs) are polydisperse in diameter and type; therefore multiple separation techniques have been developed to obtain selective tube distributions. In this work, we determined that the aqueous two-phase (ATP) separation mechanism is driven by the hydrophobicity of the surfactant, or combination of surfactants, covering the SWCNTs, which can be tuned by mixing different surfactants in well-defined ratios. The procedure is successfully applied to SWCNTs from different sources with various diameter (from 0.53nm to 1.2nm) and length (from 300nm to ~20um) distributions.
