1. Brief description of ionic liquids (IL)

ILs are synthesized by the reaction of a base with a strong acid. ILs are therefore salts, composed of negative and positive ions. Unlike the well-known sodium chloride (cooking salt), which is solid at room temperature, ionic liquids are salts which are in a liquid state below 100°C, and particularly at 25°C and even lower. Ionic liquids, known by the acronym RTIL for Room Temperature Ionic Liquids, are salts that are liquid at room temperature (20-25°C). For space applications, a room-temperature liquid is required, just as MMH, which it is intended to replace, is. The first RTIL, ethylammonium nitrate, was described in 1914 and has a melting point of 12°C. It is generally accepted that the anion (negative ion) is more important in controlling the physical properties of IL, and that the nature of the cation (positive ion) affects IL's stability and reactivity. As a result, physical properties...