Micellar growth and network formation in acidic solutions of a sulfobetaine zwitterionic surfactant triggered by an inorganic salt.

Micellization (formation of wormlike structures) of 3-(N-erucamidopropyl-N,N-dimethyl ammonium)propane sulfonate (EDAS) in the presence of an inorganic salt, iron chloride (FeCl3), in acidic conditions is studied using static and dynamic rheological measurements and small-angle X-ray scattering (SAXS). Infrared spectroscopy, single crystal X-ray, and UV-visible spectroscopy are used to further investigate the mechanisms of viscosity and elasticity and the enhancement and formation of an elastic gel-like solution induced by Fe3+ in HCl. The nature of the interaction is characterized to be hydrogen bonding between the amide groups of EDAS and coordinated water in trans-[FeCl2(H2O)4]Cl structure.