A Route for Bulk Separation of Semiconducting from Metallic\nSingle-Wall Carbon Nanotubes

Abstract

Substantial separation of single-wall carbon nanotubes (SWNTs) according to type (metallic versus\nsemiconducting) has been achieved for HiPco and laser-ablated SWNTs. We presently argue that stable\ndispersions of SWNTs with octadecylamine (ODA) in tetrahydrofuran (THF) originate from the physisorption\nand organization of ODA along the SWNT sidewalls in addition to the originally proposed zwitterion model.\nFurthermore, the reported affinity of amine groups for semiconducting SWNTs, as opposed to their metallic\ncounterparts, contributes additional stability to the physisorbed ODA. This provides a venue for the selective\nprecipitation of metallic SWNTs upon increasing dispersion concentration, as indicated by Raman\ninvestigations.