STRUCTURAL AND DYNAMIC PROPERTIES OF POLYMER-LIKE REVERSE MICELLES

A dramatic increase in the viscosity of reverse micellar solutions of lecithin in isooctane by up to a factor of 106 upon the addition of a small amount of water can be observed. Evidence is presented that the formation of viscoelastic solutions in the system lecithin/isooctane/water is due to the water-induced aggregation of lecithin molecules into flexible cylindrical reverse micelles and the subsequent formation of a transient network of entangled micelles. The existence of cylindrical aggregates in these solutions is in agreement with the results from systematic small-angle neutron scattering (SANS) measurements at different water to lecithin molar ratios and different lecithin volume fractions (Φ). The viscoelastic behavior of these solutions and the static and dynamic properties of the transient network formed at lecithin concentrations above the overlap concentration Φ* are then characterized by using a combination of dynamic light scattering, SANS, and rheological measurements. © 1990 American Chemical Society.