Selectively Coating Specific Chiralities of Single Walled Carbon Nanotubes Using Co-Surfactant Solutions

Single walled carbon nanotubes (SWCNT’s) generally contain a mixture of different (n,m) chiralities, and must be separated from the overall mixture to be used in different applications. Previously we have shown that specific co-surfactant ratios of sodium dodecyl sulphate (SDS) and sodium deoxycholate (DOC) can be utilized in the separation of specific chiral species. Using these different ratios of SDS to DOC it is possible to selectively coat specific chiralities with DOC among unsorted SDS coated SWCNT’s. Here, we have utilized dialysis as a means to understand the time needed for the DOC coating of each chirality in the mixture. Two different dialysis setups were used; Slide-A-Lyzer MINI Dialysis Devices and Mini Dialysis Kit. The Slide-A-Lyzer contained cups to hold the solution which could then be inserted into a conical tube containing the co-surfactant buffer solution whereas the Mini Dialysis Kit contained an inverted floating tube with the dialysis membrane located on the cap of the tube. The rate of replacement of surfactants from SDS to DOC on the surface of SWCNTs proved to be different for both the dialysis methods. Furthermore, the time required to coat a specific chirality was lowered by adjustments made in the dialysis procedure such as replacing the buffer frequently and using a stir plate.