Crystal Ice Becomes Square-Shaped in Graphene Sandwich

It turns out that ice water turns into a new form entirely when placed between two layers of graphene. While ice normally forms into crystals in the beautifully symmetric tetrahedral shapes seen in snowflakes and on the surface of frozen ponds, it will actually become square-shaped when pressed between layers of graphene.

Understand how water interacts with graphene is important for graphene's future applications. For example, researchers need to know how water might be transported through nanometer-scale channels in natural and artificial membranes. For example, the aquaporin protein-mediated flow across biological cell membranes is down to a balance between hydrophobic and hydrophilic interactions with channel surfaces. Knowing how these processes work is important for possibly creating graphene channels.

With graphene "pores" the situation is different. The cross section is planar rather than circular. In addition, the pressure exerted on the water is so high that hydrogen bond interactions with the graphene surface are overcome by the attractive van der Waals atomic interaction that draws together the graphene planes.

In this latest experiment, a graphene monolayer was deposited on an electron microscope grid. This layer was exposed to a small amount of water and covered with another layer of graphene. While much of the water was squeezed out, the water that remained became square-shaped.

The findings reveal a bit more about how graphene interacts with water and how physics shape water. This is especially important to note when it comes to using graphene for future applications.

The findings are published in the journal Nature.

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