It is documented that measurements related to supercooled liquids could significantly contribute to the fundamental understanding of liquid state. To obtain additional relevant data, we studied the temperature resolved thermodynamic properties, density, viscosity, and Raman spectroscopy of a deeply supercooled equimolar water – ethylene glycol (EG) binary mixture (EWEGM). After removing impurities that can act as nucleation sites, EWEGM exhibited a rather atypical behavior. Namely, the DSC data revealed at even the lowest cooling rate applied (0.1 0C/min) a regular crystallization at -43 0C did not occur; instead, a glass transition, Tg, was detected at -127 0C. The EWEGM’s heat capacity at room temperature (2.7 J 0C-1 g-1) is only slightly lower than that of the ideal mixture, which is defined as a weighted linear combination of the contributions of water and EG. On further cooling, in the vicinity of the Tg, the specific heat capacity decreases from 2.3 to 1.3 J g-1 K-1. In order to learn more about the intramolecular interactions, the density and viscosity of EWEGM were measured as a function of temperature. In the temperature interval from +25 to -70 0C, the density linearly increases while the predicted ideal curve exhibits a negative deviation from linearity. The viscosity measurement from +20 to -100 0C indicates that EWEGM behaves as a fragile liquid; its viscosity is higher than that of the predicted ideal behavior. The Grunberg–Nissan parameter G, which is considered a measure of the intensity of interaction between different molecules, was found to be a function of temperature. The comparison of the Raman spectra of water, EG and EWEGM measured in the temperature interval from +20 to -150 0C was used to rationalize the observed peculiar behavior of EWEGM.

Peculiar thermodynamic behavior of deeply supercooled equimolar water-ethylene glycol mixture

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