Stability of the amorphous state in the system water—1,2-Propanediol

Abstract For the same water contents, the stability of the wholly amorphous state of the aqueous solutions of 1,2-propanediol is much greater than that for all the solutions previously studied by us with glycerol, dimethylsulfoxide, ethanol, and ethylene glycol. To the degree that cyroprotection is related to that stability, 1,2-propanediol should be a better cryoprotectant than all these other compounds. The aqueous solutions of 1,2-propanediol have a simple behavior. No hydrate cyrstallizes on cooling, and for intermediate concentrations, on warming, after fast cooling, only ice crystallizes from the wholly amorphous state—first cubic, then hexagonal. The great stability of the amorphous state is shown by the critical warming rates above which no crystallization occurs, as well as by the difficulty in crystallizing on cooling.