Aqueous two-polymer phase extraction (ATPE) is an effective method for isolating individual (n,m) species of single-wall carbon nanotubes (SWCNTs) from multiple specie mixtures, with control of individual SWCNT specie isolation usually achieved by competing two or more surfactants against the nanotube surface. In this work, we quantified the effects of ATPE solution parameters on SWCNT extraction conditions using a recently reported near-infrared fluorescence emission monitoring method. Specifically, polyethylene glycol (PEG) molecular mass was shown to have little effect on the surfactant concentrations required for (n,m) extraction, while surfactant chemistry was observed to significantly modulate the surfactant packing structures around the SWCNTs, leading to large changes in extraction conditions for different individual (n,m) SWCNTs. In addition, distinct surfactant ratios were found to extract specific (n,m) SWCNTs, supporting a hypothesized competitive adsorption mechanism model of SWCNT sorting. These results provide valuable insights into the underlying mechanisms behind ATPE-based SWCNT separations, towards further development and optimization of the ATPE method.

Effects of surfactant chemistry and polymer choice on single-wall carbon nanotube extraction conditions in aqueous two-polymer phase extraction

ACS Spring 2022

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