Dynamics of water confined in self-assembled monoglyceride–water–oil phases

The dynamics of water confined in various self-assembled liquid-crystalline phases of the system Dimodan U/J–R(+)-limonene–water have been investigated by dielectric relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 # n/GHz # 50). For all phases, two water-related Debye processes were detected, one slightly slower, the other considerably slower, than bulk water. Besides these bulk-like and slow-water relaxations, a further fraction of water does not appear in the dielectric spectra due to strong interactions with the interface (bound water). Increasing the water content of the inverse hexagonal (HII) phase leads to an increase in both bulk-like and bound water, whereas the amount of slow water remains constant. Furthermore, the bulk-like water relaxation times accelerate until they reach the pure-water value when approaching the saturation line. This finding is supported by differential scanning calorimetry (DSC), which also confirms the presence of three types of water in liquid-crystalline confinement.