Solvation Effects in Phase Transitions in Soft Matter

Abstract

Phase transitions in polar binary mixtures can be drastically altered even by a small amount of salt. This is because the preferential solvation strongly depends on the ambient composition. Together with a summary of our research in this problem, we present some detailed results on the role of antagonistic salt composed of hydrophilic and hydrophobic ions. These ions tend to segregate at liquid-liquid interfaces and selectively couple to water-rich and oil-rich composition fluctuations, leading to mesophase formation. In our two-dimensional simulation, the corasening of the domain structures can be stopped or slowed down, depending on the interaction parameter (or the temperature) and the salt density. We realize stripe patterns at the critical composition and droplet patterns at off-critical compositions. In the latter case, charged droplets emerge with considerable size dispersity in a percolated region. We also give the structure factors among the ions, accounting for the Coulomb interaction and the solvation interaction mediated by the composition fluctuations.

23 pages, 10 figures, to appear in Journal of Physics: Condensed Matter

References in corpus (5)

• Surface tension of electrolytes: Hydrophilic and hydrophobic ions near an interface
• Surface tensions and surface potentials of acid solutions
• Precipitation in aqueous mixtures with addition of strongly hydrophilic or hydrophobic solute
• Nonionic and ionic surfactants at an interface
• Phase-Separation Transition in Liquid Mixtures Near Charged Objects

Cited by in corpus (12)

• Charged colloids in an aqueous mixture with a salt
• Mesoscale phenomena in solutions of 3-methylpyridine, heavy water, and an antagonistic salt
• Structure Formation due to Antagonistic Salts
• Electrophoretic mobility of a water-in-oil droplet separately affected by the net charge and surface charge density
• Microphase separation in oil-water mixtures containing hydrophilic and hydrophobic ions
• Electric double layer composed of an antagonistic salt in an aqueous mixture: Local charge separation and surface phase transition
• How antagonistic salts cause nematic ordering and behave like diblock copolymers
• The vanishing water/oil interface in the presence of antagonistic salt
• Selective solvation in aqueous mixtures: Interface deformations and instability
• Nano-domain formation in charged membranes: Beyond Debye-Huckel approximation
• Diffuse-Layer Capacitance at the Potential of Zero Charge in Binary Mixtures
• Microscopic understanding of ion solvation in water