  Using molecular dynamics simulations we study the dynamics of a water-like
TIP5P model of water in hydrophilic and hydrophobic confinement. We find that
in case of extreme nanocofinement such that there is only one molecular layer
of water between the confinement surface, the dynamics of water remains
Arrhenius with a very high activation energy up to high temperatures. In case
of polar (hydrophilic) confinement, The intermediate time scale dynamics of
water is drastically modified presumably due to the transient coupling of
dipoles with the effective electric field due to the surface charges.
Specifically, we find that in the presence of the polar surfaces, the dynamics
of monolayer water shows anomalous region -- namely the lateral mean square
displacement displays a distinct superdiffusive intermediate time scale
behavior in addition to ballistic and diffusive regimes. We explain these
finding by proposing a simple model. Furthermore, we find that confinement and
the surface polarity changes the vibrational density of states specifically we
see the enhancement of the low frequency collective modes in confinement
compared to bulk water. Finally, we find that the length scale of
translational-orientational coupling increases with the strength of the
polarity of the surface.
