Structure formation due to antagonistic salts

Akira Onuki, Shunsuke Yabunaka, Takeaki Araki, Ryuichi Okamoto

Research output: Contribution to journalReview article

16 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)59-64
Number of pages6
JournalCurrent Opinion in Colloid and Interface Science
Volume22
DOIs
Publication statusPublished - Apr 1 2016
Externally publishedYes

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Keywords

  • Antagonistic salt
  • Charge inversion
  • Ion adsorption
  • Mesophases
  • Selective solvation

ASJC Scopus subject areas

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry

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