Clusters in a mixture of an "amphiphilic" ionic liquid and a nonionic liquid: theoretical study

Area of Science:

• Physical Chemistry
• Materials Science
• Thermodynamics

Background:

• Understanding liquid mixtures is crucial for designing new materials.
• Ionic liquids (ILs) and nonionic liquids (nILs) exhibit unique properties.
• Predicting phase behavior in IL-nIL mixtures is complex.

Purpose of the Study:

• To theoretically describe heterogeneous mixtures of ionic liquids and nonionic liquids.
• To analyze the influence of amphiphilicity on IL-nIL mixture behavior.
• To predict phase separation and microheterogeneity in these systems.

Main Methods:

• Utilizing a Flory-Huggins type lattice approach.
• Analyzing the difference in affinities between IL ions and nIL molecules.
• Investigating system behavior based on composition and amphiphilicity.

Main Results:

• Mixtures form two macrophases if affinity differences are small.
• Microheterogeneity emerges above a threshold amphiphilicity.
• Ion or nonionic molecule clusters form depending on composition and affinity.
• Small ion clusters and potentially large nonionic molecule clusters are predicted.
• Cavity nucleation in ILs and ion clusters in IL vapor are also predicted.

Conclusions:

• The amphiphilicity of ionic liquids dictates phase behavior in nonionic liquid mixtures.
• Tunable microheterogeneity can be achieved by controlling IL-nIL interactions.
• The study provides insights into the complex phase diagrams of IL-nIL systems.