C.M. Sims, J.A. Fagan
National Institute of Standards and Technology,
Keywords: SWCNTs, separations, aqueous two phase extraction, ATPE, partition coefficient, fluorescence
Summary:Methods for rapidly determining the aqueous surfactant concentration conditions that yield upper or lower polymer phase extraction for specific (n,m) species of single-wall carbon nanotubes (SWCNTs) in aqueous two-polymer phase extraction (ATPE) separations are a missing component limiting rapid development and optimization of the ATPE technique. Here, we describe the use of near-infrared fluorescence measurements on single-phase dispersions of SWCNT species mixtures to determine these partition coefficient conditions without performing ATPE separations. This new methodology enables dramatically swifter determination of partitioning conditions for individual (n,m) species and their handed enantiomers, while using dramatically less material and without the ambiguity of mass transfer limitations or interfacial absorption present when conducting the ATPE separation itself. The ability to fully describe the partitioning conditions for each (n,m) and (m,n) is expected for multiple surfactant composition competitions and surfactant variants. Investigation of complicating factors such as temperature effects, polymer compositions, SWCNT properties, and the redox environment are likewise enabled and will also be described.