Rheology of cubic blue phases

Oliver Henrich, Kevin Stratford, Peter V. Coveney, Michael E. Cates, Davide Marenduzzo

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

We study the behaviour of cubic blue phases under shear flow via lattice Boltzmann simulations. We focus on the two experimentally observed phases, Blue Phase I (BPI) and Blue Phase II (BPII). The disclination network of Blue Phase II continuously breaks and reforms under steady shear, leading to an oscillatory stress response in time. For larger shear rates, the structure breaks up into a Grandjean texture with a cholesteric helix lying along the flow gradient direction. Blue Phase I leads to a very different response. Here, oscillations are only possible for intermediate shear rates -- very slow flow causes a transition of the initially ordered structure into an amorphous network with an apparent yield stress. Larger shear rates lead to another amorphous state with different structure of the defect network. For even larger flow rates the same break-up into a Grandjean texture as for Blue Phase II is observed. At the highest imposed flow rates both cubic blue phases adopt a flow-aligned nematic state. Our results provide the first theoretical investigation of sheared blue phases in large systems, and are relevant to understanding the bulk rheology of these materials.
Original languageEnglish
Pages (from-to)10243-10256
Number of pages14
JournalSoft Matter
Volume9
Issue number43
Early online date9 Sep 2013
DOIs
Publication statusPublished - 21 Nov 2013

Keywords

  • blue phases
  • shear flow
  • Lattice Boltzmann simulations
  • oscillatory stress response
  • shear rates
  • Grandjean texture
  • cholesteric helix

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    Henrich, O., Stratford, K., Coveney, P. V., Cates, M. E., & Marenduzzo, D. (2013). Rheology of cubic blue phases. Soft Matter, 9(43), 10243-10256. https://doi.org/10.1039/c3sm50228g