Influence of different variables on SWCNT sorting by gel chromatography

Resumen del póster presentado a la Carbon Nanoscience and Nanotechnology Conference (NanoteC), celebrada en Dublin (Irlanda) del 31 de agosto al 3 de septiembre de 2016.Typically, during the production of single-walled carbon nanotubes (SWCNTs), mixtures of various chirality species are synthesized. The electronic structure of SWCNTs, described by the chiral vector (n,m), determines their unique electrical and optical properties. Dueto these properties, SWCNTs have found potential applications in numerous fields. In many cases, the separation between semiconducting and metallic SWCNTs is needed for electronic applications. In the present work, we study process variables in the separation of SWCNTs by a gel chromatography method. Two types of SWCNTs were used: high-pressure carbon monoxide disproportionation (HiPco) SWCNTs and are discharge SWCNTs. Besides, in order to study the process selectivity dependence on the surface chemistry, the initial SWCNTs were functionalized. The experimental procedure of the chromatography column consisted of 3 steps: firstly, the SWCNTs were dispersed in a surfactant (sodium dodecyl sulfate (SDS) or pluronic F-68) in order to have a stable dispersion and avoid aggregation of SWCNTs. Different concentrations of the SWCNT initial dispersion were investigated (2, 1, 0.5, 0.25, 0.1 mglmq. Next, ultracentrifugation was performed to remove residual catalyst particles, amorphous carbon, and tube bundles. Once the SWCNTs are purified and individualized, Sephacryl gel was used to sort metallic and semiconducting SWCNTs. Different column lengths and retention times were investigated. Elution was done using a surfactant and the different fractions were collected sequentially. The collected fractions were characterized by Raman spectroscopy and absorption spectroscopy. The spectroscopy results show that the former fraction are enriched in SWCNTs in resonance via metallic transitions (E11M) and the latter fractions mainly contained SWCNTs in resonance via E22S. The results show that the technique effectively separates the SWCNTs. In addition, it was found that the selection process depends on the origin of the SWCNTs material and it is highly affected by the surface chemistry. Besides, the concentration of the raw SWCNTs dispersion and the length of the column play an important role towards the separation of single-chirality SWCNTs. The optimum conditions are reached by low SWCNT concentrations and long columns.This work has been funded by MINECO and European Regional Deve1opment Fund (ENE2013-48816-C5-5-R "NANOSOL-MAT"), CSIC (project 2015801011 "lntramural"), Government of Aragón and European Social Fund (DGA-ESF-T66 "Grupo Consolidado") and European Commission (H2020-MSCA-ITN-2014-ETN 642742 "Enabling Excellence").Peer reviewe