Low-Frequency Dielectric Investigations into the Phase Behavior of Glyceryl Monoolein/Water Systems

A series of glyceryl monoolein/water liquid crystal systems containing 15%, 20%, 30%, and 35% w/w water have been investigated using dielectric spectroscopy over a frequency range of 10-3−106 Hz and a temperature range of 20−90 °C in order to facilitate association of the lyotropic and thermotropic phase behavior with the dielectric response. The phase boundaries of the mixes were determined independently using hot stage microscopy. The frequency-dependent dielectric spectra of systems containing lamellar, cubic, and hexagonal phases are reported and have been modeled using circuits corresponding to generalized Maxwell−Wagner responses. More specifically, the systems were found to correspond to a parallel bulk capacitance and conductance in series with a Maxwell−Wagner blocking capacitance, which was associated with an adsorbed layer at the electrode surfaces. An additional dispersion was observed corresponding to a series RC circuit, which was associated with charge transport across the lipid bilayers. I...