Electrostatically controlled isolation of debundled single-walled carbon nanotubes from nanoplatelet dispersant

Abstract

Individually dispersed single-walled carbon nanotubes (SWCNTs) were isolated and stabilized from electrostatically tethered nanoplatelets in aqueous solution, following nanoplatelet-assisted exfoliation. SWCNT isolation was achieved by precipitating nanoplatelets with cations and by concurrent usage of appropriate surfactants to stabilize SWCNTs. It was found that the precipitation of nanoplatelets induced by monovalent cations was due to the ionic screening effect, whereas ion exchange was the main cause for nanoplatelet aggregation when divalent cations were used. When the above processes are optimized, isolation of pure SWCNTs with yield greater than 90% can be achieved. Effects of ion valency, ion size, reaction time, concentration of SWCNTs and surfactant type for the separation process are discussed. The structure and composition of the exfoliated SWCNTs were characterized using various microscopy and spectroscopy tools. The above exfoliation and separation approach does not noticeably affect the electronic state of the SWCNTs, and is thus highly attractive for applications where optimal SWCNT properties are desired.