Polymer-like structure of lecithin reverse micelles in the lecithin+water+cyclohexane system

摘要

The lecithin reverse micelles with and without containing water incyclohexane at 25.0degC were characterized by static (SLS) and dynamic light scattering (DLS) experiemnts.The molar amss M~0 and hydrodynamic radius R_H~0 of the micelle determined at infinite dilution have increased with increasing water content W_0,demonstrating that the micelles grow in mass and insize with water uptake into them.The vlues of R_H~0 as a function of M~0 have been successfully analyzed with the use of the wormlike spherocy linder model.The results have revealed that the micelles with cotaining water assume a shape of rather flexible cylinders with the stiffness parameter lambda~(-1)=11.0 nm and the crosssectional diameter D=5.2 nm.It is alos found that the intermolecular distance between hydrophobic tails of two adjacent lecithin molecules on the micellar surface is about 1.2 nm without regard to water content W_0.The micellar growth with increasing lecithin concentration has also been found to occur accompanying the structural evolution by combining information from SLS and DLS results.