Self-assembly of Asymmetric Architectures: Study of the Phase Behavior of an ABAC Block Copolymer

ORAL

Abstract

We have investigated the bulk phase behavior of the asymmetric tetrablock poly(cyclohexylethylene-b-ethylene-b-cyclohexyethylene-b-dimethylsiloxane) (CECD) in order to elucidate the effects of asymmetry created by introducing a third chemically distinct block to the well-studied CEC triblock. These tetrablock polymers are especially attractive due to the potential of degrading the D block, leaving a mechanically robust polyolefin triblock nanoporous material. Starting with CEC triblocks that self-assemble into different morphologies (hexagonally packed cylinders and lamellae), varying amounts of D have been added, creating two series of polymers along distinct isopleths. A combination of small-angle x-ray scattering, transmission electron microscopy and dynamic mechanical spectroscopy have revealed the complex phase behavior of these asymmetric polymers. Addition of as little as nine percent D by volume drastically changes the tetrablock morphological behavior as compared to their precursor CEC triblocks. These promising results exhibit the influence of asymmetry on the self-assembly of complex architectures in block copolymers.

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Authors

  • Michael Bluemle

    University of Minnesota, Department of Chemical Engineering and Materials Science

  • Guillaume Fleury

    University of Minnesota, Department of Chemical Engineering and Materials Science

  • Timothy Lodge

    University of Minnesota, Department of Chemical Engineering and Materials Science, University of Minnesota Department of Chemistry and Department of Chemical Engineering and Materials Science, Univ of Minnesota-Twin Cities, University of Minnesota, Departments of Chemistry and Chemical Engineering and Materials Science, University of Minnesota, Department of Chemical Engineering and Materials Science, University of Minnesota

  • Frank Bates

    University of Minnesota Department of Chemical Engineering and Materials Science, University of Minnesota, Department of Chemical Engineering and Materials Science, Department of Chemical Engineering and Materials Science, University of Minnesota