Efficient Separation of (6,5) Single-Walled Carbon Nanotubes Using a 'Nanometal Sinker'

摘要

Single-walled carbon nanotubes (SWNTs) are one-dimensional conducting nanosized molecular wires that possess remarkable electrical, mechanical, thermal, and optical properties.Although selective syntheses and the subsequent separation of SWNTs have been reported, the general difficulties in synthesizing SWNTs of a specific chirality means that SWNT chirality sorting has been a long-awaited technique for the realization of practical applications of SWNTs. These compounds may be especially useful in the field of nanoelectronic devices since the properties of the SWNTs depend on their size and electronic structures. Zheng and co-workers reported the separation of (6,5)-and (9,1)- enriched SWNTs from a sample of SWNTs dissolved in an aqueous solution of oligo single-stranded DNA (GT)_(30) by using size-exclusion chromatography (SEC). Dai and co-workers have described the separation of SWNTs with a small range of (not single) chiralities using SEC for oligo-single-stranded DNA-wrapped SWNTs. Recently, some fluorine-based polymers have been found to selectively dissolve semiconducting SWNTs. Papadimitra-kopoulos and co-workers reported that helical assemblies of flavin mononucleotide dissolve SWNTs, and have succeeded in the isolation of samples with an 85 % chirality enrichment of (8,6) SWNTs using the chirality-dependent affinity of the dissolved SWNTs. Hersam and co-workers reported that the density-gradient ultracentrifugation (DGU) technique is powerful enough to separate SWNTs of different diameters. Strano and co-workers described the separation of covalently functionalized andnonfunctionalized SWNTs by using the difference in their densities, although the fine sorting of SWNTs that have very similar diameters was difficult.