14 DAY TRIAL // Water is probably one of the strangest substances known to man, mainly due to some mind baffling properties that seem to surprise scientists on a daily basis. It is the only known substance to exist in a free state in all three phases - gaseous, liquid and solid. As it freezes, it has a lower density than that of the liquid phase, as a gas it is one of the lightest gases on Earth, it has high surface tension, high heat capacity, and in the liquid state water is virtually incompressible.
Scientists decided to study one of water's less known properties, namely the transition point to the glassy phase. A glassy state is what physical chemists call a sub-state of matter. Glassy water is a kind of ice, however while glassy water and ice have identical chemical signatures, they are extremely different in structure. Glassy water, unlike ice, does not present a crystalline structure.
Austen Angell, professor at the Arizona State University Regents and the leader of the study, says that scientists know a great deal about glassy states of other substances such as silicates and a series of metals, but, while metals behave in a predictable way, water presents an anomalous behavior. For example, metals' glassy states usually present a steady increase in heat capacity until the transition temperature is reached. Heat capacity represents the amount of energy absorbed by a body, in order to increase its temperature by one degree.
As metal forms of matter reach the transition point towards the glassy state, or the glassy temperature, they experience a doubling in heat capacity, and change from a solid phase to liquid viscous phase. On the other hand, the water barely suffers a change in heat capacity while the glassy state is being heated, and only above 136 K it will finally experience a slight rise in heat capacity. When the temperature reaches 150 K it suffers a sudden transition from glassy state and crystallizes into ice.
While trying the reverse effect, meaning to cool the water ice towards the glassy state, water starts acting up again as the heat capacity remains unchanged until reaching 250 K, after which it rises very rapidly in relation to the drop in temperature. This basically means that water does not have the same glassy transition point for both situations.
By studying water in nanoconfined environments, Angells was capable to determine the possible cause for the behavior of heat capacity of water while being subjected to temperatures ranging from 250 to 150 K. He argues that, when placed in nanoscopic environments, water will no longer crystallize when passing the glassy transition point. Water does not have the heat-capacity jump characteristics between the glassy phase and the ice phase as seen in all other glass states, but its special hydrogen bond network enables it to increase its heat capacity until reaching 220 K, in order to change phase to the glassy one, near 136 K.