Static structure factor of polymerlike micelles: Overall dimension, flexibility, and local properties of lecithin reverse micelles in deuterated isooctane

We report a systematic investigation of the static structure factor S(q,c) of polymerlike reverse micelles formed by soybean lecithin and trace amounts of water in deuterated isooctane using small-angle neutron scattering and static light scattering. The experimental data for different concentrations in the dilute and semidilute regime cover approximately three decades of scattering vectors. The data have been analyzed using polymer renormalization-group theory and a nonlinear least-squares fitting procedure based upon a numerical expression for the single chain scattering function of a wormlike chain with excluded-volume effects. Furthermore, the influence of interaction effects on the static structure factor have been successfully examined within a modified random-phase approximation. Additional information on the local scale has been extracted by applying indirect Fourier transformation and square-root deconvolution techniques. We demonstrate that we can determine structural properties such as the micellar cross-section profile and flexibility as well as quantitatively incorporate the influence of micellar growth and excluded-volume effects on S(q,c).