Single-step isolation of carbon nanotubes with narrow-band light emission characteristics

Abstract

Lack of necessary degree of control over carbon nanotube (CNT) structure has remained a major impediment factor for making significant advances using this material since it was discovered. Recently, a wide range of promising sorting methods emerged as an antidote to this problem, all of which unfortunately have a multistep nature. Here we report that desired type of CNTs can be targeted and isolated in a single step using modified aqueous two-phase extraction. We achieve this by introducing hydration modulating agents, which are able to tune the arrangement of surfactants on their surface, and hence make selected CNTs highly hydrophobic or hydrophilic. This allows for separation of minor chiral species from the CNT mixture with up to 99.7 ± 0.02% selectivity without the need to carry out any unnecessary iterations. Interestingly, our strategy is also able to enrich the optical emission from CNTs under selected conditions.

One-step sorting of single-walled carbon nanotubes using aqueous two-phase extraction in the presence of basic salts

“…Biphasic separation without chemical modulators. We started the study by conducting a differentiation of SWCNT in the absence of basic salts by using the previously determined starting parameters 30 . As can be seen, these conditions already gave somewhat preliminary separation of CNTs ( Fig.…”

“…Recently, we observed that higher resolution may be obtained upon the addition of ammonia 30 . However, we noticed that over time the change in ammonia water concentration might hurt the result of ATPE separation of CNTs.…”

“…Stepwise physical separation of these phases and subsequent combination with fresh complementary top/bottom solutions of particular composition enables fractionation of the material. At present, such routine gives rise to the isolation of SWCNTs of particular electronic character 26,27 , chirality 23,[28][29][30] and even handedness 28 both in the small- 21,24,29 and since recently also in the large-diameter regime 28 .…”

“…Commonly, the ATPE of SWCNTs is conducted in the multistep fashion to isolate the broadest possible spectrum of species one by one. We 30 and other groups 22,29 have recently started exploring the possibility of carrying out the separation in a reduced number of steps. For this purpose, we study the parameter space of the system to find the conditions able to yield particular SWCNT species ideally in a single step.…”

Aqueous two-polymer phase extraction of single-wall carbon nanotubes using surfactants

“…Different strategies with respect to isolation of puried populations have also been reported; in my lab we tend to apply generalized processing workows to make several separations with the goal to collect pure, or enriched populations of all (n,m) structures present. Other groups have reported optimized short step routes to isolate specic (n,m) structures, [26][27][28] but with the typical cost for such simplication being that all other species are aggregated and discarded. Both strategies can be useful given time constraints and the easier adoption and dissemination of recipe methods, and will be described in more detail in the next section.…”