Phase Separation of Polymer Mixtures with Highly Concentrated Ions

The fluctuation of electrostatic potentials and the dielectric contrast between species often play a crucial role in the liquid-liquid phase separation of electrolytes, but the effect of correlation between the two on the phase behavior remains elusive. Accordingly, we develop a Ginzburg-Landau theory that simultaneously accounts for the two effects for liquid mixtures containing polymer and ionic liquid. Our theory suggests that both effects can be equally important to consider the trend of the phase boundary of the liquid-liquid phase separation involving highly concentrated ions. Moreover, our present results of ionic liquids compare favorably with those calculated by the Gaussian approximation (or the one-loop expansion) of self-consistent field theory. We also show that a comparison between theory and experiment suggests that the fluctuation effect may also be significantly suppressed in ionic liquids.<div class="grammarly-disable-indicator"> </div>