Advances and applications of supercritical carbon dioxide microemulsions with or without ionic liquids

Supercritical carbon dioxide (scCO₂) has gained prominence in green chemistry due to its eco-friendly nature and unique properties, including low viscosity, nearly zero surface tension, and tunable characteristics. However, its nonpolar nature limits applications to nonpolar systems. The development of scCO₂ microemulsions with polar cores, especially those incorporating ionic liquids, addresses this limitation and expands its use across diverse fields such as cleaning, personal care, food, pharmaceuticals, materials science, and oil and gas recovery, while reducing environmental impact. Despite progress, challenges remain in understanding the thermodynamic phase behavior, nanostructure formation, and molecular dynamics of these systems. Additionally, their potential in catalysis, metal-organic frameworks (MOFs) synthesis, and polymer foaming is underexplored. This review systematically examines advancements in scCO₂ microemulsions, bridging fundamental research with applications, and highlights their promise for driving innovation in sustainable industrial processes and advancing green chemical solutions.