title: Effect of polyelectrolyte-surfactant complexation on Marangoni transport at a liquid-liquid interface.
abstract: Complexation of surfactants and oppositely charged polyelectrolytes is expected to alter Marangoni transport at a fluid interface compared to either single component system due to altered interfacial tension isotherms and mass transfer rates as well as adsorption irreversibility effects. We investigate Marangoni transport at the oil/water interface by passing mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and cationic polyelectrolyte poly(3-(2-methylpropionamide)propyl) trimethylammonium chloride-acrylamide (poly[AM-MAPTAC]), or rinsing solutions, over an oil/water interface in a radial, stagnation point flow. The displacements of adsorbed tracer particles are recorded through optical microscopy. The net displacement, defined as the sum of the displacements occurring during the adsorption and desorption stages of one application and rinsing cycle, is up to 10 times greater for complexing surfactant/polymer mixtures compared to either single component system. The enhanced net displacement is largely determined by the enhanced transport upon adsorption, while the reverse displacement that would normally occur upon rinsing is partially suppressed by partially irreversible polymer adsorption at the oil/water interface. In addition to effects of complexation on interfacial tension gradient induced flow, complexation effects on the bulk, and possibly interfacial, viscosity also influence the interfacial transport.
authors.affiliation: Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Dunér
authors.affiliation: Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Kim
authors.affiliation: Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States. Electronic address: tilton@cmu.edu.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Tilton
authors.affiliation: Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Garoff
authors.affiliation: Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Przybycien
keywords: Cationic polymer; Interfacial tension gradient; Marangoni convection; Particle transport; Polymer/surfactant complexation; Surfactant