Directly crosslinked dextran gels for SWCNT separation

The gel column chromatography method allows high-throughput and high-purity single-wall carbon nanotube (SWCNT) separation. However, the role of the gel in this system has not been fully understood. In this study, five gels with different dextran concentrations were synthesized by directly crosslinking dextran with epichlorohydrin. The low dextran concentration gels work for metal/semiconductor separation and diameter sorting of semiconducting SWCNTs. This is evidence that the chemical structure in the gel that is responsible for the selective adsorption of semiconducting SWCNTs is dextran. However, high dextran concentration gels did not adsorb SWCNTs, although the adsorption site was dextran. Micro-Raman measurements on gel slices revealed that the high dextran concentration gel has a pore size too small to allow deep diffusion of SWCNTs. Not only the chemical structure but also the physical structure is important for designing high-performance gels for SWCNT separation in the near future.