Freezing delay of water droplets in a vacuum caused by polyol addition

Droplets of pure water and polyol aqueous solutions with a diameter of several tens of micrometers were introduced into a vacuum to observe their freezing processes. The freezing time, i.e. the time elapsed from droplet generation to freezing, was found to become delayed as the polyol concentration increases. It was also found that the freezing time does not show significant dependence on the type of polyol at the same concentration. The observed delay caused by the addition of polyols is explainable by a plausible decrease in the homogeneous-ice nucleation temperature rather than by a drop in the vapor pressure.