Dynamic Crossover of Water Relaxation in Aqueous Mixtures: Effect of Pressure

In this Letter, we present results of dielectric measurements of water-propylene glycol oligomer mixtures at ambient and high pressure. The ? relaxation process that emerges with the addition of water exhibits unexpected behavior at elevated pressure. These features indicate local motions of water molecules as the origin of this relaxation process. In addition, we observe a pressure-induced change of the dynamics in the water-related relaxation; such a crossover occurs near the glass transition of the mixture and significantly differs from properties observed for confined water.