Frank Bates

March 8, 2016 - 11:00am
Wright Rieman Auditorium

"Structure and Dynamics of Block Polymer Micelles"
Spring 2016 Colloquium Series

Speaker: Frank Bates
Chemical Engineering & Materials Science
University of Minnesota
Abstract: Block copolymers belong to a broad class of amphiphilic compounds that includes soaps, lipids and nonionic surfactants. 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. This presentation will explore the fundamental thermodynamic and kinetic factors that control micelle shape and dynamics based on small-angle x-ray and neutron scattering (SAXS and SANS) experiments and cryogenic transmission and scanning 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, linked to a vanishingly small critical micelle concentration. As a consequence, molecular exchange is rapidly extinguished with increasing molecular weight resulting in non-ergodic behavior. These concepts will be discussed with respect to molecular architecture, concentration and state of micelle order.
Poster: PDF
Host: Professor Joachim Kohn
~ Coffee/tea will be served prior to lecture ~