Title: Dynamically morphing microchannels in liquid crystal elastomer coatings containing disclinations

Abstract

Liquid crystal elastomers (LCEs) hold a major promise as a versatile material platform for smart soft coatings, since their orientational order can be predesigned to program a desired dynamic profile. In this work, we introduce temperature-responsive dynamic coatings based on LCEs with arrays of singular defects-disclinations that run parallel to the surface. The disclinations form in response to antagonistic patterns of the molecular orientation at the top and bottom surfaces, imposed by the plasmonic mask photoalignment. Upon heating, an initially flat LCE coating develops linear microchannels located above each disclination. The stimulus that causes a non-flat profile of LCE coatings upon heating is the activation force induced by the gradients of molecular orientation around disclinations. To describe the formation of microchannels and their thermal response, we adopt a Frank-Oseen model of disclinations in patterned director field and propose a linear elasticity theory to connect the complex spatially-varying molecular orientation to the displacements of the LCE. The thermo-responsive surface profiles predicted by the theory and by the finite element modeling are in good agreement with the experimental data; in particular, higher gradients of molecular orientation produce a stronger modulation of the coating profile. The elastic theory and the finite element simulationsmore » allow us to estimate the material parameter that characterizes the elastomer coating’s response to the thermal activation. The disclinations containing LCEs show potential as soft dynamic coatings with a predesigned responsive surface profile.« less

Authors:

Babakhanova, Greta  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5027-5673"
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Golestani, Youssef M. ^[1]; Baza, Hend  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-0445-1672"
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Afghah, Sajedeh ^[2]; Yu, Hao ^[1]; Varga, Michael ^[1]; Wei, Qi-Huo ^[1]; Shiller, Paul  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-9714-8527"
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Selinger, Jonathan V.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-4982-2457"
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Selinger, Robin L. B.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6519-9685"
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Lavrentovich, Oleg D.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-0128-0708"
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+ Show Author Affiliations

1. Advanced Materials and Liquid Crystal Institute, Kent, OH (United States); Kent State Univ., Kent, OH (United States)
2. Kent State Univ., Kent, OH (United States)
3. Univ. of Akron, OH (United States)

Publication Date:

2020-11-12

Research Org.:

Kent State Univ., Kent, OH (United States)

Sponsoring Org.:

USDOE Office of Science (SC); National Science Foundation (NSF)

OSTI Identifier:

1822204

Alternate Identifier(s):

OSTI ID: 1712790

Grant/Contract Number:  

SC0019105

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 128; Journal Issue: 18; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Microchannel; Elastic modulus; Soft matter; Finite-element analysis; Linear elasticity; Plasmonics; Liquid crystals; Spin coating; Crystallographic defects; Polymers