Separation of carbon nanotubes into chirally enriched fractions

Abstract

A mixture of single-walled carbon nanotubes (“SWNTs”) is separated into fractions of enriched chirality by preparing an aqueous suspension of a mixture of SWNTs and a surfactant, injecting a portion of the suspension on a column of separation medium having a density gradient, and centrifuging the column. In some embodiments, salt is added prior to centrifugation. In other embodiments, the centrifugation is performed at a temperature below room temperature. Fractions separate as colored bands in the column. The diameter of the separated SWNTs decreases with increasing density along the gradient of the column. The colored bands can be withdrawn separately from the column.

1 . A method for preparing a column of liquid separation medium comprising:
 preparing a plurality of aqueous solutions of liquid comprising IODIXANOL and sodium dodecyl sulfate, each solution having a different density,   placing the solutions one at a time into an empty tube while the tube is inclined at an angle of about 10 degrees with respect to vertical, the first solution going into the tube having the highest density, and then in order of decreasing density afterward such that mixing is minimized between solutions, and   allowing the solutions in the tube to diffuse into each other, thereby preparing a column of liquid separation medium.