BETTER UNDERSTANDING VITRIFICATION

Peter Mazur, who published together with Stanley Leibo and David Whittingham the first successful cryopreservation of mammalian embryos (mouse using slow freezing in 1972 and an authority on non-equilibrium thermodynamics stated : Embryologists should learn more about thermodynamics.

See here a few things resumed.

Entropy?is a?scientific?concept that is most associated with a state of disorder, randomness, or uncertainty in other words a measure of the molecular disorder, or randomness, of a system.

It is also the measure of a system’s thermal?energy?per unit?temperature?that is unavailable for doing useful?work. Because work is obtained from ordered?molecular?motion, the amount of?entropy?is also a measure of the molecular disorder, or randomness, of a system as already said above.

Kauzmann showed that the entropy of a liquid decreases rapidly on cooling towards the kinetic glass transition temperature and extrapolates to unreasonable values at lower temperature.

The?glass–liquid transition, or?glass transition, is the gradual and?reversible?transition in?amorphous?materials from a hard and relatively brittle "glassy" state into a viscous or rubbery state as the temperature is increased.?An amorphous solid that exhibits a glass transition is called a?glass. The reverse transition, achieved by?supercooling?a?viscous liquid?into the glass state, is called?vitrification.

Thermodynamics, with Planck's statement of the third law, shows that the entropy of a liquid cannot be less than the entropy of a glass with the same enthalpy. ?Enthalpy is the sum of a thermodynamic system's internal energy?and the product of its pressure and volme.

The?third law of thermodynamics?states that the entropy of a closed system at thermadynamic equilibrium?approaches a constant value when its temperature approaches?absolute zero. This constant value cannot depend on any other parameters characterizing the system, such as pressure or applied magnetic field. At absolute zero (zero kelvins)) the system must be in a state with the minimum possible energy

This is the thermodynamic condition violated by the Kauzmann extrapolation and it suggests a thermodynamic glass transition.

The temperature where the extrapolated liquid entropy meets the crystal entropy is now called the Kauzmann temperature.

The Kauzmann paradox and associated Kauzmann temperature are two of the most widely debated topics in glass science over the past eighty years. Both conceptualized by Walter Kauzmann in 1948, the Kauzmann paradox occurs when some supercooled liquids apparently exhibit a negative excess entropy at temperatures above absolute zero. The Kauzmann temperature is the temperature at which the excess entropy vanishes.

References.

Rebecca S. Welch, Edgar D. Zanotto, Collin J. Wilkinson, Daniel R. Cassar, Maziar Montazerian, John C. Mauro, Cracking the Kauzmann paradox, Acta Materialia, Volume 254, 2023

Robin J. Speedy, Kauzmann's paradox and the glass transition, Biophysical Chemistry, Volume 105, Issues 2–3, 2003,

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