Structure Formation due to Antagonistic Salts

Abstract

Antagonistic salts are composed of hydrophilic and hydrophobic ions. In a mixture solvent (water-oil) such ion pairs are preferentially attracted to water or oil, giving rise to a coupling between the charge density and the composition. First, they form a large electric double layer at a water-oil interface, reducing the surface tension and producing mesophases. Here, the cations and anions are loosely bound by the Coulomb attraction across the interface on the scale of the Debye screening length. Second, on solid surfaces, hydrophilic (hydrophobic) ions are trapped in a water-rich (oil-rich) adsorption layer, while those of the other species are expelled from the layer. This yields a solvation mechanism of local charge separation near a solid. In particular, near the solvent criticality, disturbances around solid surfaces can become oscillatory in space. In mesophases, we calculate periodic structures, which resemble those in experiments.

6 pages, 8 figures, published in Current Opinion in Colloid & Interface Science

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Cited by in corpus (9)

• Theory of nonionic hydrophobic solutes in mixture solvent: Solvent-mediated interaction and solute-induced phase separation
• Salt-induced microheterogeneities in binary liquid mixtures
• Theory of electrolytes including steric, attractive, and hydration interactions
• Electric double layer composed of an antagonistic salt in an aqueous mixture: Local charge separation and surface phase transition
• Microphase separation in oil-water mixtures containing hydrophilic and hydrophobic ions
• Solvo-osmotic flow in electrolytic mixtures
• How antagonistic salts cause nematic ordering and behave like diblock copolymers
• Fluctuating hydrodynamics of dilute electrolyte solutions: systematic perturbation calculation of effective transport coefficients governing large-scale dynamics
• Recent advances in liquid mixtures in electric fields