(Invited) Advancing Characterization and Control of (n,m) Separations of Surfactant-Dispersed Single-Wall Carbon Nanotubes

Aqueous-phase processing of dispersed single-wall carbon nanotubes (SWCNTs) to isolate highly pure populations such as single (n,m) species or length resolved populations is of great interest to be scaled for advancing scientific investigations and commercial applications. Although many methods for (n,m) separation have been advanced, species refinement through surfactant-controlled aqueous two-polymer phase extraction (ATPE) is a particularly flexible, tailorable, and scalable route. However, better characterization of the separation conditions for different species, diameter ranges and lengths of SWCNTs can improve the ability to rapidly resolve different populations. In this talk I will present an advance in characterization of extraction conditions in ATPE using a continuous titration methodology to sweep surfactant and other solution component concentrations as a function of time while monitoring (n,m) specific fluorescence. This improvement is enabling dramatically enhanced throughput of screening multi-surfactant and modulating solution component effects on the ATPE partitioning and revealing simple orthogonal surfactant concentration steps to distinguish between traditionally difficult to separate species. Notably, an approximate order of magnitude improvement in resolution is simultaneously achieved, revealing previously unseen complexity and demonstrating direction independent reversibility of the underlying surfactant competition process. Examples of new effects and comparison to literature data will be presented.