(505d) The Search for High-Pressure Ice Phases in Nanoconfined Water Via Molecular Simulation

Water is a curious substance. It has many useful and interesting properties which arise out of the high polarity of the water molecule. (J. Israelachvili and H. Wennerström, Nature, 1996, 379(6562), 219–225.) This polarity leads to a rich phase behavior, with fifteen different crystal structures of ice known. These ice phases display very different properties due to differences in density, proton ordering, and hydrogen bond networks. For example, the fact that the dielectric constant of ice varies widely between phases has been known for some time (G. Wilson, R. Chan, D. Davidson, and E. Whalley, The Journal of Chemical Physics, 1965, 43, 2384.) and is a result of the strong proton ordering of some ice phases. Water, like other substances, displays interesting properties under confinement. Confinement of water on the molecular level has been experimentally shown to affect phase behavior. (M. Jazdzewska et al., Physical Chemistry Chemical Physics, 2011, 13(19), 9008–9013.) In addition to confinement, the presence of an electric field changes the phase diagram of water because of enhancement or depletion of the hydrogen bonding network. (J. Aragones et al., Physical Review Letters, 2011, 107(15), 155702.) Understanding the phase behavior of water in charged confinement is of interest to several fields, namely biological ion channels and energy storage devices. We have studied the nucleation of ice phases and the structure of water in charged porous carbons to better understand the properties of water in confinement, which are paramount in the effective design of these materials.