From ionic liquid to deep eutectic solvent : greener than greener

Abstract

Over the last decades, ionic liquids (ILs), molten salts with melting point below 100 °C, have attracted great attention due to their properties like negligible vapor pressure, high viscosity, high thermal conductivity, ionic conductivity and designable properties by varying the cations and anions, which enable them for abundant of applications as a new generation of green solvent. With further study, some problems of ILs start to expose, which mainly focus on the high cost, purity and toxicity. In the year of 2003, Abbott and coworkers reported a new kind of solvent with much lower freezing point formed with two solid components, choline chloride and urea, and they called it deep eutectic solvents (DES), which was considered to be a sub-category of ILs. Besides similar solvent properties with ILs, DES exhibits better biocompatibility and suitability for large scale applications. In replacement of conventional toxic organic solvent, ILs have been successfully utilized for various applications with the tag of greener solvent, and DESs are currently regarded as an option to ILs for similar applications but greener than ILs. This dissertation covers functional material applications, from ILs based to DESs based, from solvents to polymers, from greener to greener.