Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (P...

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Autores principales:	Jong-Soo Ahn, Su Hong Park, Na Yeon Kwon, Min Ju Cho, Sang-Hyon Paek, Dong Hoon Choi
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	polyimide crosslinking elastic modulus liquid crystal cell voltage holding ratio residual direct current voltage Organic chemistry QD241-441
Acceso en línea:	https://doaj.org/article/2681d0e60f1546c0bd15f76eb4688ed4
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spelling	oai:doaj.org-article:2681d0e60f1546c0bd15f76eb4688ed42021-11-25T18:48:10ZPhysical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer10.3390/polym132239032073-4360https://doaj.org/article/2681d0e60f1546c0bd15f76eb4688ed42021-11-01T00:00:00Zhttps://www.mdpi.com/2073-4360/13/22/3903https://doaj.org/toc/2073-4360This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents. After forming a thin film by mixing trifunctional epoxide [4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline] with the 6FDA−ODA-based PAA, it was confirmed that thermal curing at −110 °C caused an epoxy ring opening reaction, which could result in the formation of a networked polyimide not soluble in tetrahydrofuran. The crosslinked PI film showed a higher rigidity than the neat PI films, as measured by the elastic modulus. Furthermore, based on a dynamic mechanical analysis of the neat PI and crosslinked PI films, the glass transition temperatures (T<sub>g</sub>s) were 217 and 339 °C, respectively, which provided further evidence of the formation of crosslinking by the addition of the epoxy reagent. After mechanical rubbing using these two PI films, an LC cell was fabricated using an anisotropic PI film as an LC alignment film. LC cells with crosslinked PI layers showed a high voltage holding ratio and low residual direct current voltage. This suggests that the crosslinked PI has good potential for use as an LC alignment layer material in advanced LCD technologies that require high performance and reliability.Jong-Soo AhnSu Hong ParkNa Yeon KwonMin Ju ChoSang-Hyon PaekDong Hoon ChoiMDPI AGarticlepolyimidecrosslinkingelastic modulusliquid crystal cellvoltage holding ratioresidual direct current voltageOrganic chemistryQD241-441ENPolymers, Vol 13, Iss 3903, p 3903 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	polyimide crosslinking elastic modulus liquid crystal cell voltage holding ratio residual direct current voltage Organic chemistry QD241-441
spellingShingle	polyimide crosslinking elastic modulus liquid crystal cell voltage holding ratio residual direct current voltage Organic chemistry QD241-441 Jong-Soo Ahn Su Hong Park Na Yeon Kwon Min Ju Cho Sang-Hyon Paek Dong Hoon Choi Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
description	This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents. After forming a thin film by mixing trifunctional epoxide [4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline] with the 6FDA−ODA-based PAA, it was confirmed that thermal curing at −110 °C caused an epoxy ring opening reaction, which could result in the formation of a networked polyimide not soluble in tetrahydrofuran. The crosslinked PI film showed a higher rigidity than the neat PI films, as measured by the elastic modulus. Furthermore, based on a dynamic mechanical analysis of the neat PI and crosslinked PI films, the glass transition temperatures (T<sub>g</sub>s) were 217 and 339 °C, respectively, which provided further evidence of the formation of crosslinking by the addition of the epoxy reagent. After mechanical rubbing using these two PI films, an LC cell was fabricated using an anisotropic PI film as an LC alignment film. LC cells with crosslinked PI layers showed a high voltage holding ratio and low residual direct current voltage. This suggests that the crosslinked PI has good potential for use as an LC alignment layer material in advanced LCD technologies that require high performance and reliability.
format	article
author	Jong-Soo Ahn Su Hong Park Na Yeon Kwon Min Ju Cho Sang-Hyon Paek Dong Hoon Choi
author_facet	Jong-Soo Ahn Su Hong Park Na Yeon Kwon Min Ju Cho Sang-Hyon Paek Dong Hoon Choi
author_sort	Jong-Soo Ahn
title	Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
title_short	Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
title_full	Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
title_fullStr	Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
title_full_unstemmed	Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer
title_sort	physical properties of thermally crosslinked fluorinated polyimide and its application to a liquid crystal alignment layer
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/2681d0e60f1546c0bd15f76eb4688ed4
work_keys_str_mv	AT jongsooahn physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer AT suhongpark physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer AT nayeonkwon physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer AT minjucho physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer AT sanghyonpaek physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer AT donghoonchoi physicalpropertiesofthermallycrosslinkedfluorinatedpolyimideanditsapplicationtoaliquidcrystalalignmentlayer
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Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer

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