Structure Sorting of Large-Diameter Carbon Nanotubes by NaOH Tuning the Interactions between Nanotubes and Gel

The structure separation of synthetic single-wall carbon nanotube (SWCNT) mixture species with diameters larger than 1.2 nm still remains a challenge. Here, an NaOH-assisted gel chromatography method is used for the structure separation of the SWCNT mixture with a diameter range of 1.2-1.7 nm, in which NaOH is used to tune the interaction between distinct (n, m) SWCNTs and gel. Incrementally increasing NaOH concentration in SWCNT dispersion selectively enhances the adsorbability of different-structure SWCNTs and enlarges their interaction difference with gel, leading to their structure separation after applying into a gel column system. On this basis, a two-step method is developed for further improving the structure purity of the separated SWCNTs by combining overloading and stepwise elution. These results are well demonstrated by the optical spectra of the separated SWCNTs. This work paves a way for single-chirality separation of large-diameter SWCNTs using gel chromatography technique and is an advanced progress in the structure control of SWCNTs.