In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Magid will use light scattering and small-angle neutron scattering (SANS) to investigate polyelectrolytes and the formation of giant micelles that are self-assembled in aqueous solutions from surfactants. In selected cases the micellar solutions will be studied in flow fields similar to those found in some of the applications for which these solutions are used. Both self-organizing and covalent polyelectrolytes are to be studied, providing a valuable bridge between what are often considered two different fields of study. The SANS experiments proposed here will provide data on chain conformations as a function of intrinsic stiffness of the polyelectrolyte chains. Of special interest are the changes in micellar length and in spatial organization (conformation) that occur with changes in surfactant concentration. This work will produce the first quantitative numbers concerning the concentration dependence of micellar growth parameters in dilute solutions. Micelles and polyelectrolytes are broadly found in biological systems, where they have a variety of structural and functional roles. They are also ubiquitous in consumer and industrial applications such as personal-care products, drug-delivery systems, viscosity modifiers in foods and in processing of polymers, drag reduction and shear-thinning in heat-exchanger fluids, paints, and surface modification of materials. Several recent theoretical advances have pointed to the need for new experimental data such as Magid will gather in her studies of thread-like micelles and the influence of polyelectrolytes on them.
