title: Surfactant and polyelectrolyte gel particles that swell reversibly.
abstract: Mixing of oppositely charged surfactants and polyelectrolytes in aqueous solutions can lead to associative phase separation, where the concentrated phase is a viscous liquid, gel, or precipitate. In recent years, this phenomenon has been exploited to form gel-like particles, ranging from approximately 100 to 4000 microm in diameter, whose stability depends on equilibrium phase behavior. As the sample composition is varied, these particles either remain stable (in a two-phase mixture) or dissolve over time. Here, we present the formation of reversibly swelling gel particles from mixtures of N,N,N-trimethylammonium-derivatized hydroxyethyl cellulose (JR-400) and sodium dodecyl sulfate (SDS), whose swelling is controlled by the ambient solution conditions. The effects of cross-linking density and surfactant concentration are investigated by gravimetry and confocal microscopy. The resulting particles have a core/shell morphology and undergo reversible swelling/collapse transitions which, depending on the cross-link density, can be either gradual or abrupt with changing SDS concentration.
authors.affiliation: Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, USA.
authors.forename: Yakov
authors.initials: Y
authors.lastname: Lapitsky
authors.forename: William J
authors.initials: WJ
authors.lastname: Eskuchen
authors.forename: Eric W
authors.initials: EW
authors.lastname: Kaler