A new way of purifying and seperating single-walled nanotubes (SWNTs, see figure) comes in the form of an efficient polyacylation using Friedel-Crafts catalysts in either nitrobenzene as a solvent or in a NaCl/AlCl3 melt. The report method provides a way for the efficient insertion not only of normal acyl chains but also of perfluorinated acyl residues or for crosslinking possibilities by using a,omega-diacyl dichlorides.