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

Abstract

The dynamics of water confined in various self-assembled liq.-cryst. phases of the system Dimodan U/J-R(+)-limonene-water have been investigated by dielec. relaxation spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν/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 dielec. 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 amt. of slow water remains const. Furthermore, the bulk-like water relaxation times accelerate until they reach the pure-water value when approaching the satn. line. This finding is supported by differential scanning calorimetry (DSC), which also confirms the presence of three types of water in liq.-cryst. confinement.