Low Toxic Ionic Liquids, Liquid Catanionics, and Ionic Liquid Microemulsions

Abstract

A review. In the future the demand of sustainable and low toxic surfactants and solvents will constantly increase. In this article, we review some new approaches to meet these requirements. Whereas ionic liqs. are often based on imidazolium ions, we will show that there are also much less toxic ones, esp. with choline as cation. Choline salts, even if solid at room temp., can advantageously be mixed with other sustainable solids to form deep eutectic solvents, i.e., "green" liqs. at room temp. Further, choline can be used to dissolve long-chain carboxylates in water thus maybe permitting new applications of soaps. Alternatively, choline and other natural cations can be part of promising low toxic cationic surfactants. By combining them with ethoxylated carboxylates, interesting charged room temp. liq. surfactant combinations can be obtained. Finally, we shortly discuss the potential benefits of ionic liqs. in microemulsions.