Quantifying (n,m) Specific SWCNT Partition Conditions in Aqueous Two-Polymer Phase Extraction

Aqueous two-polymer phase extraction is a sensitive and scalable method for extracting specific (n,m) structures of single-walled carbon nanotubes (SWCNTs). Advancement of the technique by evaluating multistep separations for (n,m) selectivity has enabled method development for the extraction of many (20+) (n,m) species of SWCNTs by competing various surfactants for the nanotube surface, however, reliance on actual separations for characterizing the process variables is slow, requires significant materials, and is subject to mass transfer and environmental artifacts. Recently we determined that fluorescence measurements could instead be utilized to probe the ATPE separation-controlling interfacial layer of surfactant on single (n,m) species of nanotubes, enabling direct quantification of solution conditions that will lead to selective extraction, but without conducting a separation. Using this method we have now screened multiple surfactant chemistries, and the effects of other ATPE parameters on the extraction condition for multiple (n,m) species. The results provide fundamental insights into the controlling chemical physics of the separation and can guide selective separation to the single enantiomer level of nanotube species. These results, and characterization of the separated fractions, will be presented.