Dynamic Behavior of Water in Lyotropic Ternary Mixtures

Abstract

The diffusion of water molecules in lyotropic mixtures of potassium palmitate/potassium laurate/water was investigated using pulsed-field gradient nuclear magnetic resonance (PFG-NMR). The self-diffusion constant of water as a function of temperature was measured in two samples having different compositions and found to be sensitive to the structures of the different mesophases. Deuterium nuclear magnetic resonance (D-NMR) experiments were also performed on a mixture containing D₂O, in a temperature rang where a rectangular mesophase (RB_a ) coexists with a lamellar (L_a ) mesophase. The diffusion data, combined with the D-NMR spectral profiles allowed for the study of the size of the mixed mesophase domains.