Adriaan VAN DEN BRUINHORST1, Jocasta ÁVILA1, Martin ROSENTHAL2, Manfred BURGHAMMER2, Alexey MELNIKOV2, Ange PELLEGRINO1, Nithavong CAM1, Margarida COSTA GOMES1
1ENS de Lyon, Lyon, France
2ESRF, The European Synchrotron, Grenoble, France
Various solid ammonium salts undergo thermal decomposition before or upon melting, rendering their fusion properties inaccessible experimentally. We could overcome this limitation by heating these salts at rates beyond their decomposition kinetics (>1000 K/s) using fast (differential) scanning calorimetry, or F(D)SC. Additionally, we developed experimental strategies that allowed us to study highly hygroscopic components with F(D)SC under dry atmosphere. By coupling FSC with synchrotron X-ray scattering and high-speed microscopy imaging, we provided evidence of melting and recrystallisation for choline chloride (see figure), three tetraethylammonium halides, and trimethylglycine (also known as betaine). Finally, we evaluated the enthalpy of fusion of studied compounds with FDSC, which is the missing link to predict the liquid window of their mixtures such as deep eutectic solvents.