Catanionic surfactants as nanospring suspensions: a model.

A model for a dilute suspension of nanosprings, whose equilibrium configuration and extension are controlled by electrical double layer forces, is presented along with a model for changing packing parameter. The dependence of viscosity on surface charge is calculated. The possibility of shear-thickening is demonstrated. It is argued that mixtures of cationic and anionic surfactants which show two peaks in viscosity and a minimum along with shear-thickening are likely candidates for this model.