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Regulating the modulus of a chiral liquid crystal polymer network by light
We report a novel way to modulate the elastic modulus of azobenzene containing liquid crystal networks (LCNs) by exposure to light. The elastic modulus can cycle between different levels by controlling the illumination conditions. Exposing the polymer network to UV light near the trans absorption ba...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Royal Society of Chemistry
2016
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5050537/ https://www.ncbi.nlm.nih.gov/pubmed/26924678 http://dx.doi.org/10.1039/c6sm00114a |
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author | Kumar, Kamlesh Schenning, Albertus P. H. J. Broer, Dirk J. Liu, Danqing |
author_facet | Kumar, Kamlesh Schenning, Albertus P. H. J. Broer, Dirk J. Liu, Danqing |
author_sort | Kumar, Kamlesh |
collection | PubMed |
description | We report a novel way to modulate the elastic modulus of azobenzene containing liquid crystal networks (LCNs) by exposure to light. The elastic modulus can cycle between different levels by controlling the illumination conditions. Exposing the polymer network to UV light near the trans absorption band of azobenzene gives a small reduction of the glass transition temperature thereby lowering the modulus. The addition of blue light addressing the cis absorption band surprisingly amplifies this effect. The continuous oscillatory effects of the trans-to-cis isomerization of the azobenzene overrule the overall net cis conversion. The influence on the chain dynamics of the network is demonstrated by dynamic mechanical thermal analysis which shows a large shift of the glass transition temperature and a modulus decrease by more than two orders of magnitude. The initial high modulus and the glassy state are recovered within a minute in the dark by switching off the light sources, despite the observation that azobenzene is still predominantly in its cis state. Based on these new findings, we are able to create a shape memory polymer LCN film at room temperature using light. |
format | Online Article Text |
id | pubmed-5050537 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | Royal Society of Chemistry |
record_format | MEDLINE/PubMed |
spelling | pubmed-50505372016-10-12 Regulating the modulus of a chiral liquid crystal polymer network by light Kumar, Kamlesh Schenning, Albertus P. H. J. Broer, Dirk J. Liu, Danqing Soft Matter Chemistry We report a novel way to modulate the elastic modulus of azobenzene containing liquid crystal networks (LCNs) by exposure to light. The elastic modulus can cycle between different levels by controlling the illumination conditions. Exposing the polymer network to UV light near the trans absorption band of azobenzene gives a small reduction of the glass transition temperature thereby lowering the modulus. The addition of blue light addressing the cis absorption band surprisingly amplifies this effect. The continuous oscillatory effects of the trans-to-cis isomerization of the azobenzene overrule the overall net cis conversion. The influence on the chain dynamics of the network is demonstrated by dynamic mechanical thermal analysis which shows a large shift of the glass transition temperature and a modulus decrease by more than two orders of magnitude. The initial high modulus and the glassy state are recovered within a minute in the dark by switching off the light sources, despite the observation that azobenzene is still predominantly in its cis state. Based on these new findings, we are able to create a shape memory polymer LCN film at room temperature using light. Royal Society of Chemistry 2016-04-07 2016-02-15 /pmc/articles/PMC5050537/ /pubmed/26924678 http://dx.doi.org/10.1039/c6sm00114a Text en This journal is © The Royal Society of Chemistry 2016 http://creativecommons.org/licenses/by/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Chemistry Kumar, Kamlesh Schenning, Albertus P. H. J. Broer, Dirk J. Liu, Danqing Regulating the modulus of a chiral liquid crystal polymer network by light |
title | Regulating the modulus of a chiral liquid crystal polymer network by light
|
title_full | Regulating the modulus of a chiral liquid crystal polymer network by light
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title_fullStr | Regulating the modulus of a chiral liquid crystal polymer network by light
|
title_full_unstemmed | Regulating the modulus of a chiral liquid crystal polymer network by light
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title_short | Regulating the modulus of a chiral liquid crystal polymer network by light
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title_sort | regulating the modulus of a chiral liquid crystal polymer network by light |
topic | Chemistry |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5050537/ https://www.ncbi.nlm.nih.gov/pubmed/26924678 http://dx.doi.org/10.1039/c6sm00114a |
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