Microphase Separation and Stability of Chiral Rafts in Colloidal Membranes

ORAL

Abstract

Colloidal membranes are an experimental system composed of rod-like chiral particles that are driven by depletion interactions to self-assemble into one-rod-length thick monolayers. Their large size enables the study of behaviors that cannot be visualized in lipid bilayers, as they are described by the same continuum theory. Membranes formed from a mixture of short right-handed rods and long left-handed rods exhibit microphase separation, wherein one rod species forms finite-sized rafts floating in a background membrane of the other rod species. This system exhibits complex membrane-mediated interactions between rafts, which depend on the depletant concentration and the chirality of the rods. In this talk I will present a Ginzburg-Landau theory that explains the existence and interactions of rafts. Consistent with recent experiments, we find that decreasing the background chirality allows rafts to form with either right-handed (in the direction preferred by chirality) or left-handed (counter to the preferred direction) twist. Further, pairs of like-twisted rafts have repulsive interactions, while pairs of oppositely-twisted rafts have attractive interactions. The theory allows for a mechanistic understanding of these behaviors.

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Presenters

  • Chaitanya Joshi

    Physics, Brandeis University

Authors

  • Chaitanya Joshi

    Physics, Brandeis University

  • Joia Miller

    Physics, Brandeis University, Brandeis University

  • Arvind Baskaran

    Physics, Brandeis University, Martin A. Fisher School of Physics, Brandeis University, Physics Department, Brandeis University

  • Gregory Grason

    Polymer Science and Engineering, University of Massachusetts - Amherst, University of Massachusetts Amherst, Polymer Science and Engineering, University of Massachusetts Amherst, UMass Amherst

  • Zvonimir Dogic

    Physics, University of California, Santa Barbara, UC Santa Barbara, Physics, University of California Santa Barbara, University of California, Santa Barbara, UCSB, Department of Physics, University of California at Santa Barbara

  • Michael F Hagan

    Chemistry, Brandeis University, Physics, Brandeis University, Brandeis University, Martin A. Fisher School of Physics, Brandeis University, Physics Department, Brandeis University

  • Aparna Baskaran

    Brandeis University, Physics, Brandeis University, Martin A. Fisher School of Physics, Brandeis University, Physics Department, Brandeis University