(Invited) Determining Surfactant Concentrations for Separation of (n,m) Chirality Swcnts in ATPE via Fluorescence Detection

In this talk I will present a methodology for rapid and quantitative determination of surfactant concentrations that result in top or bottom-phase partitioning of individual (n,m) SWCNTs species in an aqueous two-polymer phase extraction using near-infrared fluorescence measurements. This methodology enables quantitative evaluation of parameters affecting ATPE such as temperature, polymer molecular weight and composition, and surfactant choice without conducting an actual separation. Additional advantages of the technique include a very low sample concentration for measurement, rapid measurement, and no mass transfer derived limitations in interpreting results. Using the technique, we have investigated different combinations of surfactants to explore the effects of surfactant chemistry. In most cases, two transitions in the NIR fluorescence are observed with co-surfactant concentration for each (n,m) species, which we identify as differential separation of left and right-handed SWCNT enantiomers. Specific trends with (n,m) diameter and with variation of surfactant chemistry will be discussed.