Ionic Liquids in Microemulsions-A Concept To Extend the Conventional Thermal Stability Range of Microemulsions

Abstract

Ionic liqs. (ILs) have attracted more and more attention in recent years, because of their unique properties, such as low vapor pressure, high thermal stability, and wide liq. range. All studies concerning ILs in microemulsions described in literature were performed below the b.p. of water. Herein, the authors demonstrate for the 1st time the existence of high-temp. stable microemulsions under ambient pressure based on replacement of water with a room-temp. IL, ethylammonium nitrate (EAN). These systems show a thermal stability ranging from 30° up to at least 150°. Both cond. and SANS measurements are in agreement with the existence of a L2 phase (ionic liq. in oil). Dynamic light scattering and temp.-dependent SANS expts. for different EAN concns. show that swelling behavior with an increasing amt. of EAN occurs. These high-temp. stable microemulsions open a wide field of potential applications, such as for nanoparticle synthesis, new reaction media, or lubricant formulations.