(543c) Surfactant Chemistry and Counter-Ion Clouds in Bile Salt Stabilized Swcnts

Enrichment and separation of SWCNTs based on chirality has been previously achieved by subjecting bile salt stabilized aqueous suspension of SWCNTs to analytical centrifugation. The ability of bile salts to amplify relatively subtle differences in SWCNTs based on chirality to significant differences in hydrodynamic behavior can be attributed to the structure and dynamics of the counter-ion cloud surround the stabilized SWCNT in water. The counter-ion cloud is known to create an “ion wall” between surfactant coated SWCNTs, which is key for stabilizing the SWCNTs in water. Experiments on bile salts have shown that minor chemical differences (such as point mutations) in surfactant backbone or “tail” chemistry lead to drastic changes in both, the solution properties as well as their ability to stabilize SWCNTs. Here, we use atomistically detailed molecular dynamics simulations to study the free energy of separation of SWCNTs stabilized by different bile salts. Understanding the molecular mechanism underlying the interplay between the chemistry of the bile salt backbone, the structure and dynamics of the counter-ion cloud, and the hydrodynamic behavior of the surfactant stabilized-SWCNT is important for separation of SWCNTs based on chiral fractions.