Ionic surfactant-triggered renewal of the structures and properties of polyelectrolyte multilayer films.

The present study investigated the effects of ionic surfactants on polyelectrolyte multilayer (PEM) films, consisting of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS), prepared using a sequential layer-by-layer (LbL) technique. The electrostatic interaction between sodium dodecyl sulfate (SDS) and the PEMs resulted in desorption of the polyelectrolytes from the PEM films, and consequently the thickness of the PEM films was altered, as confirmed by UV-vis, XPS, and AFM studies. Two critical features of this phenomenon include the porous morphology of the SDS-treated films and the simultaneous increase in the thickness of the film. Furthermore, both the rate and amount of polyelectrolytes desorbed from the PEM films could be controlled by varying the surfactant, the outermost layer, and the reaction time. The surface morphology and thickness of the PEM films could be retuned even after formation of PEMs. Thus, controlled desorption of PEs could be an effective tool for the renewal of the structures and properties of PEMs.