Encapsulation of Ionic Liquids for Tailored Applications

This spotlight article highlights the favorable impact encapsulation of ionic liquids (ILs) has on multiple advanced applications. ILs are molten salts with many attractive properties such as negligible vapor pressure, good thermal stability, and high ionic conductivity; however, their widespread implementation in advanced applications is hampered by their relatively high viscosity, which makes them difficult to handle and results in slow mass transfer rates. The ability to encapsulate IL in a shell holds potential to impact many applications, including separations, gas sequestration, and energy storage and management, given that the capsule structure provides high surface area compared to that of bulk IL and also allows handling of the IL as a solid. Herein, we discuss encapsulation of ILs using different approaches and highlight the contributions from our lab in both capsule preparation and application. Specifically, we have developed the ability to use 2D carbon nanoparticle surfactants and interfacial polymerization to prepare capsules of IL using both IL-in-water and IL-in-oil Pickering emulsions as templates. This facile, one-step method to encapsulate ILs gives structures with beneficial performance in supercapacitors, separations, and CO2 sequestration, as discussed herein. We conclude this spotlight with an outlook on how to improve upon these systems for next-generation applications.