Adsorption of sodium dodecylsulfate on single-walled carbon nanotubes characterised using small-angle neutron scattering

Aqueous dispersions of single-walled carbon nanotubes are often made using sodium dodecylsulfate (SDS), which adsorbs to the nanotube surface to stabilise them. Despite SDS being commonly used with single-walled carbon nanotubes, there is no consensus on the structure of the adsorbed layer. Small-angle neutron and X-ray scattering results reported here show that the data can be fitted to a relatively simple core-shell cylinder model, consistent with a polydisperse nanotube core of radius 10 ˚A, surrounded by an adsorbed surfactant layer of thickness 18 ˚A and volume fraction of 0.5. This is consistent with small nanotube bundles surrounded by an adsorbed layer of extended SDS molecules.