H-2 NMR and polyelectrolyte-surfactant interactions: from micelles to monolayers to membranes

This article reviews deuterium (H-2) NMR studies of polyelectrolytes intera cting with deutero-labelled surfactants in different surfactant self-assemb led architectures, including micelles, monolayers, and bilayer membranes. I n phase-separated polyelectrolyte-surfactant micelle complexes H-2 NMR diff erentiates the loosely packed complexes formed in the presence of the relat ively stiff polyelectrolyte poly(sodium styrenesulfonate) from the tightly packed complexes formed in the presence of the relatively flexible polyelec trolyte poly(acrylic acid). Moreover, H-2 NMR reveals the presence in such complexes of a thermotropic phase transition, accompanied by anisotropic re orientations about the surfactant's long molecular axis. In surfactant mono layers coating a latex particle, H-2 NMR is employed to monitor surface ele ctrostatics as a function of added polyelectrolyte. It is discovered that f locculation of the particle dispersion by added polyelectrolyte occurs at a concentration far below that necessary to neutralize the initial surface c harge of the surfactant monolayer. In bilayer membranes it is shown that th e sensitivity of H-2 NMR to surface charge confers the ability to different iate and characterize polyelectrolyte-induced domains enriched with opposit ely-charged surfactants. (C) 1999 Elsevier Science B.V. All rights reserved .