Frank-Kasper Phases in Block Polymers: Stable or Metastable?

ORAL

Abstract

Block polymers are a class of soft materials that self-assemble at mesoscopic length scales to form a variety of ordered structures. In recent years, several experimental studies witnessed the formation of complex low-symmetry structures in sphere-forming block polymers. These structures, commonly referred to as Frank-Kasper (FK) phases, contain particles of disparate sizes packed in a tetrahedral closed-packed arrangement with multiple local coordination environments. In this work, we use self-consistent field theory (SCFT) to examine the stability of different FK phases in AB diblock copolymers. We performed extensive SCFT calculations and observed that several FK phases exist on the free energy surface of diblock copolymers. More importantly, the associated free energies differ only marginally (10-3 kBT). Recently, our group experimentally discovered two new FK phases in poly(isoprene-b-lactide) diblock copolymers. Using SCFT, we will discuss the thermodynamic stability of these phases and demonstrate the importance of various molecular parameters that govern the relative stability of these complex phases in AB diblocks.

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Presenters

  • Akash Arora

    Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Materials Science, University of Minnesota

Authors

  • Akash Arora

    Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Materials Science, University of Minnesota

  • Kyungtae Kim

    Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Materials Science, University of Minnesota, Univ of Minnesota - Twin Cities

  • Ronald Lewis

    Chemical Engineering and Materials Science, Univ of Minn - Minneapolis

  • Meijiao Liu

    Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Education Ministry, Zhejiang Sci-Tech University

  • Wei-hua Li

    Department of Macromolecular Science, Fudan Univ, Department of Macromolecular Science, Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University

  • Anchang Shi

    Department of Physics and Astronomy, McMaster University, Fudan Univ, Physics and Astronomy, McMaster University

  • Frank Bates

    Univ of Minnesota - Twin Cities, Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Materials Science, University of Minnesota

  • Kevin Dorfman

    Chemical Engineering and Materials Science, Univ of Minn - Minneapolis, Department of Chemical Engineering and Material Science, University of Minnesota, Chemical Engineering and Materials Science, University of Minnesota - Twin Cities, Department of Chemical Engineering and Materials Science, University of Minnesota