Disassembling single-walled carbon nanotube bundles by dipole/dipole electrostatic interactions

Dipole/dipole electrostatic attraction was used for the first time for disassembling the single-walled carbon nanotube (SWCNT) bundles. A self-assembled zwitterionic monolayer (SAZM) was created by modification of the SWCNT bundles with a sulfonate/quaternary-ammonium type of zwitterionic surfactants. The headgroups of the SAZM align at the terminal-end and form anti-parallel doublets. Dipole/dipole electrostatic attractions occurred readily as the SAZM approached to another. SWCNT bundles have been disassembled into individual tubes because of the strong dipole/dipole attractions. Large quantities of unbundled single-walled carbon nanotubes (SWCNTs) were obtained within a single step by this method. Concentric circular membranes containing the unbundled SWCNTs were prepared. The unbundled SWCNTs were found to have tendencies to curve around the circular direction.