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This content will become publicly available on January 9, 2019

Title: Interplay of Structure, Elasticity, and Dynamics in Actin-Based Nematic Materials

Achieving control and tunability of lyotropic materials has been a long-standing goal of liquid crystal research. Here we show that the elasticity of a liquid crystal system consisting of a dense suspension of semiflexible biopolymers can be manipulated over a relatively wide range of elastic moduli. Specifically, thin films of actin filaments are assembled at an oil-water interface. At sufficiently high concentrations, one observes the formation of a nematic phase riddled with +/- 1/2 topological defects, characteristic of a two-dimensional nematic system. As the average filament length increases, the defect morphology transitions from a U shape into a V shape, indicating the relative increase of the material's bend over splay modulus. Furthermore, through the sparse addition of rigid microtubule filaments, one can gain additional control over the liquid crystal's elasticity. We show how the material's bend constant can be raised linearly as a function of microtubule filament density, and present a simple means to extract absolute values of the elastic moduli from purely optical observations. Finally, we demonstrate that it is possible to predict not only the static structure of the material, including its topological defects, but also the evolution of the system into dynamically arrested states. Despite the nonequilibriummore » nature of the system, our continuum model, which couples structure and hydrodynamics, is able to capture the annihilation and movement of defects over long time scales. Thus, we have experimentally realized a lyotropic liquid crystal system that can be truly engineered, with tunable mechanical properties, and a theoretical framework to capture its structure, mechanics, and dynamics.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Univ. of Chicago, IL (United States). Inst. for Molecular Engineering
  2. Univ. of Chicago, IL (United States). James Franck Inst.; Univ. of Chicago, IL (United States). Dept. of Physics
  3. Univ. of Massachusetts, Amherst, MA (United States). Dept. of Physics
  4. Univ. of Chicago, IL (United States). James Franck Inst.; Univ. of Chicago, IL (United States). Dept. of Physics; Univ. of Chicago, IL (United States). Inst. for Biophysical Dynamics
  5. Univ. of Chicago, IL (United States). Inst. for Molecular Engineering; Argonne National Lab. (ANL), Argonne, IL (United States). Inst. for Molecular Engineering
Publication Date:
Grant/Contract Number:
AC02-06CH11357; DMR-1710318; MCB-1344203
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 115; Journal Issue: 2; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE; National Science Foundation (NSF); Army Research Office (ARO)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; actin; elasticity; lyotropic liquid crystal; microtubule; topological defects
OSTI Identifier:
1459902