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Title: Tunable structure and dynamics of active liquid crystals

Abstract

Active materials are capable of converting free energy into directional motion, giving rise to notable dynamical phenomena. Developing a general understanding of their structure in relation to the underlying nonequilibrium physics would provide a route toward control of their dynamic behavior and pave the way for potential applications. The active system considered here consists of a quasi–two-dimensional sheet of short (≈1 μm) actin filaments driven by myosin II motors. By adopting a concerted theoretical and experimental strategy, new insights are gained into the nonequilibrium properties of active nematics over a wide range of internal activity levels. In particular, it is shown that topological defect interactions can be led to transition from attractive to repulsive as a function of initial defect separation and relative orientation. Furthermore, by examining the +1/2 defect morphology as a function of activity, we found that the apparent elastic properties of the system (the ratio of bend-to-splay elastic moduli) are altered considerably by increased activity, leading to an effectively lower bend elasticity. At high levels of activity, the topological defects that decorate the material exhibit a liquid-like structure and adopt preferred orientations depending on their topological charge. Together, these results suggest that it should be possible tomore » tune internal stresses in active nematic systems with the goal of designing out-of-equilibrium structures with engineered dynamic responses.« less

Authors:
ORCiD logo; ; ; ORCiD logo
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
University of Chicago - Materials Research Science & Engineering Center (MRSEC); National Science Foundation (NSF); University of Chicago - Institute for Biophysical Dynamics
OSTI Identifier:
1498507
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 4; Journal Issue: 10; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Country of Publication:
United States
Language:
English

Citation Formats

Kumar, Nitin, Zhang, Rui, de Pablo, Juan J., and Gardel, Margaret L. Tunable structure and dynamics of active liquid crystals. United States: N. p., 2018. Web. doi:10.1126/sciadv.aat7779.
Kumar, Nitin, Zhang, Rui, de Pablo, Juan J., & Gardel, Margaret L. Tunable structure and dynamics of active liquid crystals. United States. doi:10.1126/sciadv.aat7779.
Kumar, Nitin, Zhang, Rui, de Pablo, Juan J., and Gardel, Margaret L. Mon . "Tunable structure and dynamics of active liquid crystals". United States. doi:10.1126/sciadv.aat7779. https://www.osti.gov/servlets/purl/1498507.
@article{osti_1498507,
title = {Tunable structure and dynamics of active liquid crystals},
author = {Kumar, Nitin and Zhang, Rui and de Pablo, Juan J. and Gardel, Margaret L.},
abstractNote = {Active materials are capable of converting free energy into directional motion, giving rise to notable dynamical phenomena. Developing a general understanding of their structure in relation to the underlying nonequilibrium physics would provide a route toward control of their dynamic behavior and pave the way for potential applications. The active system considered here consists of a quasi–two-dimensional sheet of short (≈1 μm) actin filaments driven by myosin II motors. By adopting a concerted theoretical and experimental strategy, new insights are gained into the nonequilibrium properties of active nematics over a wide range of internal activity levels. In particular, it is shown that topological defect interactions can be led to transition from attractive to repulsive as a function of initial defect separation and relative orientation. Furthermore, by examining the +1/2 defect morphology as a function of activity, we found that the apparent elastic properties of the system (the ratio of bend-to-splay elastic moduli) are altered considerably by increased activity, leading to an effectively lower bend elasticity. At high levels of activity, the topological defects that decorate the material exhibit a liquid-like structure and adopt preferred orientations depending on their topological charge. Together, these results suggest that it should be possible to tune internal stresses in active nematic systems with the goal of designing out-of-equilibrium structures with engineered dynamic responses.},
doi = {10.1126/sciadv.aat7779},
journal = {Science Advances},
number = 10,
volume = 4,
place = {United States},
year = {2018},
month = {10}
}

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