Coarse-grained model for polyelectrolyte complexation

ORAL

Abstract

Self-assembly based on co-polyelectrolyte complexation offers new opportunities for materials design. Here, oppositely charged polyelectrolytes undergo an associative process of phase separation, driven by the entropy gain associated with the release of counter-ions. Homopolymers typically self-assemble into coacervates, while block copolyelectrolytes form micelles or hydrogels. In this study, we aim to quantitatively reproduce experimental results for the phase behavior and rheology of coacervates with a coarse-grained model. Specifically, we focus on three features of the coacervate. First, there is a strong dependence of polymer concentration on the added salt concentration. Second, we show that salt is generally expelled from the coacervate phase and that our model is capable of capturing the salt partition coefficient between the coacervate and supernatant phases. Third, the model enables calculation of the mechanical response and it compares well with experimental measurements. Moreover, it captures changes in the relaxation time as a function of added salt concentration, a phenomenon referred to as "time-salt superposition". We explore the effects of model parameters on the above features of coacervates, and explain the role of short range interactions and ionic strength.

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Presenters

  • Marat Andreev

    Institute of Molecular Engineering, University of Chicago

Authors

  • Marat Andreev

    Institute of Molecular Engineering, University of Chicago

  • Lu Li

    Institute of Molecular Engineering, University of Chicago, Institute for Molecular Engineering, Univ of Chicago

  • Samanvaya Srivastava

    Univ of California, Los Angeles, Institute for Molecular Engineering, University of Chicago, Institute of Molecular Engineering, University of Chicago, Chemical and Biomolecular Engineering, University of California Los Angeles, Institute for Molecular Engineering, Univ of Chicago, University of California, Los Angeles

  • Matthew Tirrell

    Univ of Chicago, Institute for Molecular Engineering, University of Chicago, Institute of Molecular Engineering, University of Chicago, IME, University of Chicago, Institute for Molecular Engineering, Univ of Chicago, The University of Chicago

  • Alexandros Chremos

    National Institute of Standards and Technology

  • Vivek Prabhu

    National Institute of Standards and Technology, Materials Science and Engineering Division, NIST -Natl Inst of Stds & Tech

  • Jack Douglas

    National Institute of Standards and Technology, Materials Science and Engineering Division, NIST -Natl Inst of Stds & Tech

  • Juan De Pablo

    Institute for Molecular Engineering, The University of Chicago, Institute for Molecular Engineering, Univ of Chicago, Institute for molecular engineering, The University of Chicago, University of Chicago, Univ of Chicago, Institute for Molecular Engineering, University of Chicago, The Institute for Molecular Engineering, The University of Chicago, Institute of Molecular Engineering, University of Chicago