Measurement of single-wall nanotube dispersion by size exclusion chromatography
Size exclusion chromatography (SEC) is shown to be an effective method to characterize single-wall carbon nanotube (SWNT) dispersions. SEC separates nanotube dispersions by size, and an on-line viscosity detector gives intrinsic viscosity as a function of hydrodynamic size, as is determined by universal calibration. The scaling contains information about the shape of the dispersed particles. This characterization method was tested on three representative dispersions, octadecylamine functionalization (SWNT-ODA) in tetrahydrofuran (THF), butyl group functionalization (SWNT-butyl) in THF, and DNA wrapping (SWNT/DNA) in aqueous solution. Significant differences between the dispersions were found. Small-angle neutron scattering (SANS) and atomic force microscopy (AFM) produced results consistent with the SEC method.