FLOW-FIELD FLOW FRACTIONATION TO SEPARATE AND CHARACTERIZE SINGLE WALL CARBON NANOTUBES BY LENGTH

 

Jaehun Chun, Erik Hobbie and Barry Bauer

 

Flow-Field Flow Fractionation (Flow-FFF) has been a useful technique to separate various colloids, particles, and macromolecules such as polymer latexes and proteins by their sizes, taking advantage of a balance between random thermal and uniform flow-driven motions on an object of interest. We exploit Flow-FFF, equipped with on-line multi-angle light scattering (MALS) and UV-Vis photodiode array, to separate single wall carbon nanotubes (SWNTs) dispersed in aqueous medium by the use of DNA. Clear separations are demonstrated for both unfractionated SWNTs and SWNT fractions made by use of size exclusion chromatography (SEC). Rod lengths of the SWNTs are calculated from MALS and those are compared to rod lengths from hydrodynamic models based on latex sphere calibrations. Flow-FFF is capable of probing subtle differences in SWNT size distributions, which suggests that Flow-FFF may be a simple method of SWNT identification and quality assessment. Furthermore, recent progress with additional implementation of an electric field to separate SWNTs by chirality as well as length will be briefly presented.