Pressure-induced amorphization and crystallization of Choline chloride/Ethylene glycol deep eutectic solvent

The pressure-induced phase transitions of Choline chloride/Ethylene glycol (ChCl/EG) deep eutectic solvent have been studied at different rates of 0.2 and 1.0 GPa/s up to about 5.0 GPa. Two crystalline phases formed at 2.6 and 3.9 GPa with increasing pressure at lower compression rate, however, the amorphous phase solidified with superpressurized glass above 2.8 GPa at higher compression rate. The unusual results may be explained by the unique and characteristic structure of deep eutectic solvent and the supercooling induced by compression. The P versus T phase diagram of ChCl/EG deep eutectic solvent was constructed, and the solidification mechanism of ChCl-based deep eutectic solvent was discussed through the molecules packing of ChCl.