Materials Science Research Lecture
Abstract: Block copolymers belong to a broad class of amphiphilic compounds that includes soaps, lipids and nonionic surfactants, which are ubiquitous in many types of soft materials. These macromolecules assemble into micelles with molecular dimensions on the order of 5 to 50 nm in size when mixed with excess solvent that preferentially solvates one block type. The fundamental thermodynamic and kinetic factors that control micelle shape and dynamics will be discussed based on small-angle x-ray and neutron scattering (SAXS and SANS) experiments and cryogenic transmission electron microscopy results. Although the structural features displayed by amphiphilic block copolymers resemble those associated with the self-assembly of lipids and simple surfactants (e.g., spherical and cylindrical micelles and vesicles) a macromolecular architecture leads to remarkably different dynamic properties, where molecular exchange is extraordinarily sensitive to molecular weight and block configuration. These results will be presented in the context of a molecular model for chain exchange and the occurrence of non-ergodic micelle dispersions in the liquid state.
More about the Speaker: Frank S. Bates is a Regents Professor and a member of the Chemical Engineering and Materials Science department at the University of Minnesota. He received a B.S. in Mathematics from SUNY Albany and M.S. and Sc.D. degrees in Chemical Engineering from MIT. Between 1982 and 1989 Bates was a member of the technical staff at AT&T Bell Laboratories then joined the University of Minnesota where he served as department Head from 1999 to 2014. Bates conducts research on a range of topics related to polymers, with a particular focus on the thermodynamics and dynamics of block polymers, blends and solutions. He is a member of the National Academy of Engineering and the National Academy of Sciences, and the American Academy of Arts and Sciences.