Ordered structures in poly(allylamine hydrochloride) gel and sodium dodecylbenzenesulfonate surfactant complexes

We investigated the structure of poly(allylamine hydrochloride) (PAAMHCl) gel-sodium dodecylbenzenesulfonate (SDBS) surfactant complexes using small-angle X-ray scattering. PAAMHCl gels were prepared by using N,N′-methylenebisacrylamide as a cross-linking agent. These gels were complexed with SDBS below a critical micelle concentration of the surfactant. The gel–surfactant complexes (GSC) exhibited lamellar structures with an interlayer spacing of 35 Å which is less than twice the length of the stretched SDBS molecule. The effect of ionic strength on the formation and the structure of GSC were investigated. The complexes were found to be highly stable in presence of salt solutions.