Block Copolymer Nanostructures: Symmetry, Epitaxy, and Shear
Tim Lodge
Department of Chemistry and
Department of Chemical Engineering & Materials Science
University of Minnesota
Block copolymers provide an appealingly flexible route to the self-assembly of nanostructures. In dilute solution a variety of interesting, discrete micellar structures can be obtained. In more concentrated solutions and in the bulk, three dimensionally ordered phases result. A host of variables, including chain architecture (diblock vs triblock, linear vs star), molecular weight, copolymer composition, solvent selectivity, concentration, and temperature can be used to tune the structure. Synchrotron SAXS provides a powerful characterization tool for these systems, especially when combined with in situ shear cells and wide-ranging temperature control. Examples from recent work by the University of Minnesota Polymer Group at APS will be highlighted, including: new network phases in ABC copolymers; new micellar structures in dilute aqueous solution; mechanisms and epitaxial pathways of order-order transitions in concentrated copolymer solutions.