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019 Colburn Lab (302) 831-8919
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Vesicle formation and the effect of hydrotropes on surfactant solutions Mixtures of oppositely charged surfactants in aqueous solutions self-assemble into a variety of organized structures such as spherical or elongated micelles, vesicles, or lamellae depending on the type of surfactants and their relative concentrations. These structures, with length scales spanning the entire colloidal domain (1 nm to several microns), are of utmost importance in processes for the manufacture of cosmetics, paints, pharmaceuticals, and nanoparticles among others. Of these aggregates, vesicles (closed bilayers) are of keen interest for scientists because they mimic the membranes in living organisms and may find diverse applications as drug delivery devices, microreactors, or surfactant delivery systems for enhanced oil recovery. Part of this work is aimed at understanding the formation of vesicles in mixtures of oppositely charged surfactants, their properties, and structural fixation of these structures via polymerization to produce hollow spheres. The other part explores vesicle formation from the simple mixing of surfactants such as SDBS with specific hydrotropes, many of which are biocompatible. Hydrotropes are short-chained and weakly surface active molecules that cannot self-assemble into micelles. Beside vesicles, the self-assembly into other microstructures such as micelles, gels, and fibers is also possible from simply changing the relative amount of the components or by varying solution conditions such as pH. Techniques such as light scattering, small-angle neutron scattering, cryogenic transmission electronic microscopy (cryo-TEM) are used to characterize these microstructures.
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