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Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties

Some cellulose derivatives are known to exhibit thermotropic and lyotropic cholesteric liquid crystal (CLC) phases with a visible reflection feature by changing the side chains and mixing with specific solvents, respectively. Although many studies have been reported so far, most of the derivatives h...

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Autores principales: Hayata, Kenichiro, Furumi, Seiichi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835709/
https://www.ncbi.nlm.nih.gov/pubmed/31623193
http://dx.doi.org/10.3390/polym11101696
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author Hayata, Kenichiro
Furumi, Seiichi
author_facet Hayata, Kenichiro
Furumi, Seiichi
author_sort Hayata, Kenichiro
collection PubMed
description Some cellulose derivatives are known to exhibit thermotropic and lyotropic cholesteric liquid crystal (CLC) phases with a visible reflection feature by changing the side chains and mixing with specific solvents, respectively. Although many studies have been reported so far, most of the derivatives have the side chains of linear alkyl groups, but not the bulky phenyl groups. In this report, we synthesized a series of hydroxypropyl cellulose (HPC) derivatives that possessed both linear propionyl esters and bulky (trifluoromethyl)phenyl carbamates in the side chains. The reflection peaks of HPC derivatives shifted to longer wavelengths upon heating due to an increase in the CLC helical pitch. Such thermally induced shifting behavior of the reflection peak was crucially dependent on not only the propionyl esterification degree, but also the substituents in the side chains of HPC derivatives. When the side chains of HPC were chemically modified with both propionyl esters and bulky substituents such as 3,5-bis(trifluoromethyl)phenyl carbamates, the reflection peaks emerged at longer wavelengths at the same temperature. This probably happened because of the steric hindrance of bulky side chains, as supported by the empirical molecular modeling calculation. Although the occupied volumes of (trifluoromethyl)phenyl groups were independent of the CLC phase temperature with visible Bragg reflection, the substituent position, i.e., substituent orientation of trifluoromethyl groups affected the CLC phase temperature. Moreover, we found that the hydrogen bonds between carbamate moieties in the HPC side chains play an important role in the thermally induced shift of reflection peaks.
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spelling pubmed-68357092019-11-25 Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties Hayata, Kenichiro Furumi, Seiichi Polymers (Basel) Communication Some cellulose derivatives are known to exhibit thermotropic and lyotropic cholesteric liquid crystal (CLC) phases with a visible reflection feature by changing the side chains and mixing with specific solvents, respectively. Although many studies have been reported so far, most of the derivatives have the side chains of linear alkyl groups, but not the bulky phenyl groups. In this report, we synthesized a series of hydroxypropyl cellulose (HPC) derivatives that possessed both linear propionyl esters and bulky (trifluoromethyl)phenyl carbamates in the side chains. The reflection peaks of HPC derivatives shifted to longer wavelengths upon heating due to an increase in the CLC helical pitch. Such thermally induced shifting behavior of the reflection peak was crucially dependent on not only the propionyl esterification degree, but also the substituents in the side chains of HPC derivatives. When the side chains of HPC were chemically modified with both propionyl esters and bulky substituents such as 3,5-bis(trifluoromethyl)phenyl carbamates, the reflection peaks emerged at longer wavelengths at the same temperature. This probably happened because of the steric hindrance of bulky side chains, as supported by the empirical molecular modeling calculation. Although the occupied volumes of (trifluoromethyl)phenyl groups were independent of the CLC phase temperature with visible Bragg reflection, the substituent position, i.e., substituent orientation of trifluoromethyl groups affected the CLC phase temperature. Moreover, we found that the hydrogen bonds between carbamate moieties in the HPC side chains play an important role in the thermally induced shift of reflection peaks. MDPI 2019-10-16 /pmc/articles/PMC6835709/ /pubmed/31623193 http://dx.doi.org/10.3390/polym11101696 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Communication
Hayata, Kenichiro
Furumi, Seiichi
Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title_full Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title_fullStr Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title_full_unstemmed Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title_short Side Chain Effect of Hydroxypropyl Cellulose Derivatives on Reflection Properties
title_sort side chain effect of hydroxypropyl cellulose derivatives on reflection properties
topic Communication
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835709/
https://www.ncbi.nlm.nih.gov/pubmed/31623193
http://dx.doi.org/10.3390/polym11101696
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