As described in Section 5.1, the water expelled from the reverse
micelle is dispersed in the nonpolar solvent below Tc. This leads to the
fact that another interfacial water layer at the solvent appears below
Tc, in addition to that at the surfactant. Moreover, the surface area at
the solvent is comparable to that at the surfactant because most of the
bulk-like water molecules are extracted from the reverse micelle.
However, the amplitude of the fast component does not increase
below Tc compared with that above Tc, as shown in Fig. 6(c). Studies of
water at hydrophobic liquid surfaces suggest that the hydrogen-bond
network of water at the surface is weakly formed and that the onset of
bulk-phase behavior occurs very close to the interface [45–47]. Hence,
it is likely that the interfacial water at the solvent mostly serves as
bulk-like water and does not show the local motion that is observed in
the interfacial water at the surfactant. As a result, the interfacial water
at the solvent does not contribute to the fast relaxation component
below Tc.