Acid-mediated isolation of individually dispersed SWCNTs from electrostatically tethered nanoplatelet dispersants

Individually dispersed single-walled carbon nanotubes (SWCNTs) in aqueous solution were isolated from electrostatically tethered α-zirconium phosphate nanoplatelet dispersants by precipitating the nanoplatelets with an acid. By using an appropriate amount of acid along with either anionic or nonionic surfactants, about 80% of exfoliated, purified SWCNTs can be retrieved and stabilized in aqueous solution; the separated nanoplatelets can also be recycled. In comparison with nonionic surfactants, certain types of anionic surfactants can facilitate the separation between the nanoplatelets and SWCNTs, while others could retard the separation. The above acid separation approach is highly versatile and the isolated SWCNTs can be subsequently processed to remove surfactants, to introduce functionality, or to achieve effective sorting of SWCNTs for various sensor, microelectronic device, and composite applications.