title: Isolation of >1 nm Diameter Single-Wall Carbon Nanotube Species Using Aqueous Two-Phase Extraction.
abstract: In this contribution we demonstrate the effective separation of single-wall carbon nanotube (SWCNT) species with diameters larger than 1 nm through multistage aqueous two-phase extraction (ATPE), including isolation at the near-monochiral species level up to at least the diameter range of SWCNTs synthesized by electric arc synthesis (1.3-1.6 nm). We also demonstrate that refined species are readily obtained from both the metallic and semiconducting subpopulations of SWCNTs and that this methodology is effective for multiple SWCNT raw materials. Using these data, we report an empirical function for the necessary surfactant concentrations in the ATPE method for separating different SWCNTs into either the lower or upper phase as a function of SWCNT diameter. This empirical correlation enables predictive separation design and identifies a subset of SWCNTs that behave unusually as compared to other species. These results not only dramatically increase the range of SWCNT diameters to which species selective separation can be achieved but also demonstrate that aqueous two-phase separations can be designed across experimentally accessible ranges of surfactant concentrations to controllably separate SWCNT populations of very small (∼0.62 nm) to very large diameters (>1.7 nm). Together, the results reported here indicate that total separation of all SWCNT species is likely feasible by the ATPE method, especially given future development of multistage automated extraction techniques.
authors: Jeffrey A
authors: JA
authors: Fagan
authors: ‡Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
authors: Erik H
authors: EH
authors: Hároz
authors: §National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors: Rachelle
authors: R
authors: Ihly
authors: ∥Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089, United States.
authors: Hui
authors: H
authors: Gui
authors: §National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
authors: Jeffrey L
authors: JL
authors: Blackburn
authors: Jeffrey R
authors: JR
authors: Simpson
authors: Stephanie
authors: S
authors: Lam
authors: Angela R
authors: AR
authors: Hight Walker
authors: ‡Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
authors: Stephen K
authors: SK
authors: Doorn
authors: Ming
authors: M
authors: Zheng
keywords: separation; single-wall carbon nanotube; two-phase extraction