(204d) High-Fidelity Single-Column Selective Desorption of Swcnts through the Modulation of Co-Surfactant States Around Carbon Nanotubes
Single-chirality single walled carbon nanotubes (SWCNTs) have unique optoelectronic properties that can be utilized in specific applications, such as photovoltaics and biosensors. However, due to the large variety of SWCNTs and the difficulty of separation, the application of chiral SWCNTs is still limited. The post-synthetic separation of single wall carbon nanotubes (SWCNTs) has been studied with great interest in the past decade. While high-fidelity separations of SWCNTs by their (n,m) type have been demonstrated, a simple, high-throughput method is still desired. Our previous work has highlighted the importance of surfactant structure along SWCNT sidewalls in the separation mechanism. Here we report the selective desorption of a wide range of single-chirality (n,m) fractions by a single column process with a single elution profile due to the formation of different thermodynamic co-surfactant states around SWCNTs. High-purity fractions of (n,m) nanotubes are obtained with high yield once a specific ratio of sodium dodecyl sulfate (SDS)/sodium deoxycholate (DOC) co-surfactant solution is used. By modulating the surfactant concentration of sodium dodecyl sulfate (SDS) and sodium deoxycholate (DOC), these single-chiral nanotubes are also obtained at their specific ratio even with long elution times, different total surfactant background concentrations, and different temperatures. The elution of only one (n,m) type at a specific co-surfactant ratio while other types are exposed to more surfactant suggests that each (n,m) type forms a thermodynamically-stable surfactant structure in the co-surfactant solution. These thermodynamic equilibrium states result in entropy-driven desorption at specific SDS/DOC co-surfactant ratios, enabling high-fidelity separations of each (n,m) type in a single column. These findings provide a promising foundation for the development of large-scale, high-throughput chromatographic separations that can collect each (n,m) type sequentially.