(346a) Measured Structures of Adsorbed Surfactant Shells On Doubly Sorted Nanotubes

One key that determines the behavior of single-wall carbon nanotubes in solution, whether for their processing or optical properties, is the interfacial layer of bound surfactant or macromolecules.  This layer helps control these properties by controlling access to the nanotube surface, affecting the local dielectric environment, having desorption/adsorption kinetics that affect colloidal aggregation, and by displaying different functional groups to the environment.  In this talk I will present results for the characterization of interfacial layer on SWCNTs that have been doubly or triply sorted for properties including water-filling, their length distribution, and the electronic type / species.  These finely separated populations exhibit dramatically narrow sedimentation coefficients reminiscent of biological macromolecules when characterized in an analytical ultracentrifuge.  Taking advantage of the high resolution, we explore the changes in the bound layer while varying the surfactant molecule for multiple populations.  The implications of the measured dependencies for processing control and improved separations will be discussed.