Water layers on ice submerged in antifreeze liquid: Nano-forcemetry

Ice is an important material on Earth. However, despite the extensive research conducted on ice surfaces exposed to vacuum or vapor, studies of liquid-ice interfaces are limited. In this study, we used an atomic force microscope cooled to -10 °C to observe force-distance curves at the interfaces of ice and four antifreeze liquids: decane, octane, octanol, and saltwater (an aqueous solution of NaCl). The approach force curves recorded in decane and octane indicated the presence of liquid water layers on the ice wafers. Based on our accumulated knowledge of vacuum-ice interfaces, we hypothesized that the free OH groups on the ice exposed to the liquid alkanes would induce surface disordering of the ice and form a water layer. Force-distance curves observed in octanol and saltwater suggested that the ice wafers were directly exposed to these liquids without a water layer in between. The surface disordering of the ice may have been prevented in these liquids because they can form hydrogen bonds with the OH groups on the ice.