Fluctuations in number of water molecules confined between nanoparticles.

We used molecular dynamics computer simulations to study the character of interactions between two nanoscale graphene plates in water and also between plates made of "carbon" atoms that have different interaction strength with water. Fluctuations in the number of water molecules in the confined space between plates are qualitatively similar when the plates are made of graphene or when the plates contain "carbon" atoms with weaker "carbon"-water interaction strength. We also observed that these fluctuations are strongly enhanced compared to the fluctuations observed next to a single plate. If the character of water fluctuations in the confined space determines the character of interactions, then it is possible to conclude that the interaction between graphene plates in water is hydrophobic.