Phase Transitions in Soft Matter Induced by Selective Solvation

We review our recent studies on selective solvation effects in phase separation i np olar binary mixtures with a small amount of solutes. Such hydrophilic or hydrophobic particles are preferentially attracted to one of the solvent components. We discuss the rol eo f antagonisti cs alt composed of hydrophilic and hydrophobic ions, which undergo microphase separation at wateroil interfaces leading to mesophases. We then discuss phase separation induced by a strong selective solvent above a critical solute density np ,w hich occurs far from the solvent coexistence curve. We also give theories o fi onic surfactant systems and weakly ionized polyelectrolytes including solvation among charged particles and polar molecules. We point out that the Gibbs formula for the surface tension needs to include an electrostatic contribution in the presence of an electric double layer.