WATER SELF-DIFFUSION IN LYOTROPIC LIQUID-CRYSTALS - PULSED GRADIENT SPIN-ECHO NMR AND SIMULATION TECHNIQUES

This review is devoted to summarizing the most recent results in the f ield of water self-diffusion in lyotropic liquid crystals (LLC) using Pulsed Field Gradient Spin-Echo NMR experiments. The main purpose of s uch studies is to provide a deeper understanding of the factors determ ining the mobility of water molecules in these systems. The water self -diffusion results have been widely used to clarify the solution prope rties of many organized mixtures. The review is divided into two compl ementary sections. In the first part we deal with a generalized theore tical analysis of NMR self-diffusion experiments in LLC mesophases. Ex perimental results concerning lamellar, hexagonal and lyotropic nemati c phases are obtained on binary systems such as: potassium palmitate/w ater, bis(2-ethylhexyl) sulfosuccinate (Aerosol OT)/water and ammonium perfluorononanoate/water. In the second part we report some recent fi ndings of the water self-diffusion in LLC systems obtained by computer simulation techniques. The Pulsed Field Gradient Spin-Echo NMR experi ments have been simulated and new results are presented on the structu ral properties of normal hexagonal phases.