C.M. Sims, J.A. Fagan
National Institute of Standards and Technology,
Keywords: carbon nanotube, CNT, fluorescence, automation, separation, metrology
Summary:The exceptional optical, thermal, and electronic properties of single-wall carbon nanotubes (SWCNTs) have enabled their use across a broad range of applications, including photonics, biomedicine, and sensors. However, the full realization of these properties, and thus, SWCNT technology development, requires the isolation of each (n,m) specie from commercially synthesized mixtures, which contain multiple individual species. (n,m) species isolation through surfactant-controlled aqueous two-phase extraction (ATPE) is an effective and scalable, liquid-phase processing method for these isolations, however, better characterization of the extraction conditions for different species will improve the ability to rapidly process commercial mixtures into their individual (n,m) components. Towards this, we recently advanced a fluorescence-based spectroscopy method for determining extraction conditions of specific (n,m) species SWCNTs and their enantiomers via ATPE. Here, we report a significant advance in the throughput and precision of this fluorescence monitoring method through development of a semi-automated gradient dilution process. The improved speed and precision of this new method enables dramatically swifter evaluation of partitioning conditions, while enabling the distinguishing of difficult to separate (n,m) species and their handed enantiomers. In addition, the increased resolution of the method reveals previously inaccessible complexity in the underlying surfactant competition process in ATPE. Examples of new effects and comparison to literature data will also be presented.