Order–disorder transition induced by surfactant micelles in single-walled carbon nanotubes dispersions
Review by Bryan Hassell: AP 255 Fall 11
From: Order–disorder transition induced by surfactant micelles in single-walled carbon nanotubes dispersions, E. Nativ-Roth et. al, Soft Matter, 2010, 6, 5289–5292
Single walled carbon nanotubes (SWNT) with their all-carbon composition and interesting geometries are characterized by a unique combination of electrical and mechanical properties. To utilize their properties, you have to disperse them in aqueous media for various applications. It's becoming evident that the coupling between molecular and colloidal interactions leads to non-trivial structures when the dimensions and geometry of the nanostructures are commensurate. The results that this group showed used transmission electron microscopy at cryogenic temperatures (Cryo-TEM) and was of spontaneously formed microns-long islands of orientationally ordered SWNT in macroscopically homogeneous dispersions of ionic surfactant micelles.
In Fig. 1a, b and d they present images taken from dispersions of SWNT(0.5–1 wt%) in solutions of spherical micelles of an ionic surfactant, cetyl trimethyl ammonium bromide (CTAB). The solution concentrations are above the critical micelle concentration (cmc) of the native surfactant but within the isotropic phase of the spherical micelles and far from their liquid crystalline (LC) transition. The SWNT dispersions are optically isotropic, and the viscosity of the dispersion is similar to that of the native surfactant solution.