High-yield and high-throughput single-chirality enantiomer separation of single-wall carbon nanotubes

Abstract

Single crystals of single-wall carbon nanotubes are desired for precise analysis of the physical properties of carbon nanotubes, necessitating preparation of single-chirality enantiomers in large quantities. In this work, by investigating the effects of surfactant concentration and temperature on the enantiomer separation, we achieved large-scale single-chirality enantiomer separation for the first time using triple surfactant stepwise elution chromatography with a naturally produced dextran-based gel as the column medium. Through one-round programmed separation, milligram-scale of (11,–5) (equivalent to (5,6)) and (6,5) enantiomers were separated from CoMoCAT carbon nanotube soot. The separation yields estimated from the optical absorbance at 280 nm were 5.6% (11,−5) and 2.6% (6,5) per load of all SWCNTs, which correspond 28% and 13% per load of total (11,–5) and (6,5) enantiomers, respectively. This high yield is mainly attributed to the narrow chirality distribution and high concentrations of (11,–5) and (6,5) in CoMoCAT and the high-resolution selectivity of the triple surfactant system for two enantiomers. The high throughput is sufficient to prepare high-purity (11,–5) and (6,5) bucky papers.