Unveiling the Melting Point and High-Temperature Crystal Structure of Choline Chloride and Its Eutectic Mixtures using Simultaneous Fast Sca

Deep eutectic solvents (DESs) have recently been gaining scientific interest in many research areas as alternative, more sustainable, liquid media. DESs are prepared by mixing two or more components, the melting point of the resulting mixture being significantly lower than that of its pure constituents. Fusion properties are key for the prediction of the DES’s liquid window. Choline chloride (ChCl) is a solid at ambient conditions and is the most common DES constituent. Its fusion properties are inaccessible owing to thermal decomposition. Here, we propose to use ultra-fast scanning calorimetry in combination micro-XRD to overcome this limitation and elucidate the melting point as well as the high-temperature crystal structure of ChCl and its mixtures. This allows for the correct description of the liquid window for many DESs. Moreover, this data is of high relevance for the scientific community as they provide the missing link for the design of novel DESs for specific applications.