Photo Alignment Materials with High Sensitivity to Near UV Light.

Makita, Yutaka; Natsui, T.; Kimura, Shin-ichi; Nakata, Shoichi; Kimura, Masayuki; Matsuki, Yasuhiko; Takeuchi, Yuto

doi:10.2494/photopolymer.11.187

Cited by 49 publications

(43 citation statements)

References 2 publications

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“…The peak at 260 nm was assigned to the dimerized moieties of the mesogenic group due to the cycloaddition reaction of the chalcone moiety. 14 The DR values of the peak at 260 nm were positive. This result indicated that the dimerized moieties were aligned parallel to the electric vector of the incident LPUV light.…”

Section: Photoinduced Anisotropy Of Polymer Filmsmentioning

confidence: 99%

“…The peak around 320 nm was assigned to the mesogenic group containing the chalcone derivative with the trans conformation, while the peak around 260 nm in the spectra of the polymer 1 film was attributed to the dimer structure formed by the photoreaction. 14 The photodimerization and photoisomerization are known as a possible photoreaction of the photoreactive molecules like the chalconyl or the cinnamoyl groups. We investigated the photoreaction of the chalconyl groups by FT-IR measurements.…”

Section: Photoreaction Of Polymer Filmsmentioning

confidence: 99%

“…[13][14][15][16][17][18][19] Makita et al reported that the good LC alignment was observed for the LC cell using the polymer film with a chalcone moiety compared to the cinnamate polymer film when the deep UV light was cut off. [13][14][15][16] So the chalconyl moiety is a good photosensitive group. Poly(4-methacryloyloxy chalcone) (PM4Ch) or poly(4 -methacryloyloxy chalcone) (PMCh) were employed as a photoalignment film.…”

Section: Introductionmentioning

confidence: 99%

“…The LC molecules in the LC cells using the linearly polarized UV (LPUV) irradiated PM4Ch or PMCh film were aligned to perpendicular to the electric vector of the in- cident LPUV light. 13,14 In the case of the photoalignment films on which LC molecules were aligned perpendicular to the electric vector of the incident LPUV light, the generation of pretilt angle would require the two step LPUV irradiation as suggested by Iimura et al 20 We thought that the alignment behavior of the LC molecules would be easily improved by the liquid crystalline polymer surface where mesogenic groups having similar chemical structure to that of the LC molecules existed. In this study, we investigated the photoreaction of the chalcone-based LC polymers films.…”

mentioning

confidence: 99%

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Photoreaction of New Chalcone-Based Side Chain Type Liquid Crystalline Polymers and Alignment Behavior of Liquid Crystal on the Irradiated Films

Mutoh

Tsutsumi

Koide

2002

Polym J

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ABSTRACT:We investigated the photoreaction of the side chain type liquid crystalline polymers with a chalcone derivative in the side chain. The polymer films were irradiated with linearly polarized UV (LPUV) light (350 nm) under different conditions. The photodimerization of the chalconyl moieties would mainly occur due to a decrease in the peak assigned to the chalconyl moiety by UV-vis spectroscopy measurements. The extent of the photoreaction in the liquid crystalline (LC) state is larger than that in the solid state after spin-coating and in the locked-in LC state after annealing. The LC cell was fabricated from the polymer film irradiated with LPUV light to examine the alignment properties of low molar mass LC molecules on them. A mixture of low molecular liquid crystal with the dichroic dye was filled in the LC cell. The low molecular liquid crystal was easily aligned parallel to the electric vector of the incident exposed LPUV light in the LC cell with the polymer film irradiated in the LC state.KEY WORDS Chalcone / Liquid Crystalline Polymer / Photodimerization / Photoalignment / The alignment of liquid crystalline (LC) molecules plays an important role for liquid crystalline displays (LCDs). The rubbing process has been mainly employed for the uniaxial orientation of the LC molecules. However, the rubbing process has many disadvantages for LCDs such as generation of electrostatic charge and dust. Therefore, many methods of alignment technique for LC molecules are focused on rubbing free methods. Photoalignment procedure is recognized as one of rubbing free methods and is investigated as one of candidates that overcome the generation of electrostatic charge and dust for the rubbing process. 1,2 Photoalignment procedure is based on photochemical reactions such as photoisomerization, photodimerization (photocrosslinking) and photodecomposition. With respect to photoisomerization, polymers containing an azobenzene derivative were intensively investigated. [3][4][5] The reversible photoreaction of the azobenzene moieties in the polymer induced a reversible change in the alignment direction of low molecular weight LC molecules. Generally photodimerization of photosensitive groups in the polymer was employed to obtain a stable alignment of low molecular weight LC molecules.Photodimerization of the cinnamoyl chromophore in the polymer film have been studied in detail. The polymer films containing dimerized moiety of cinnamoyl group have been investigated as a photoalignment material by many researches. 2, 6-10 Schadt et al. have obtained the alignment film by photodimerization of cinnamoyl group in the poly(vinyl 4-methoxycinnamate). LC molecules in the LC cell were aligned perpendicular to the electric vector of the incident LPUV light. 6 Alignment behavior of LC molecules would be easily improved by the liquid crystalline polymer surface where mesogenic groups are aligned. Kawatsuki et al. had reported alignment properties of side chain type liquid crystalline polymers with the cinnamoyl groups as an alignmen...

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Section: Photoinduced Anisotropy Of Polymer Filmsmentioning

confidence: 99%

Section: Photoreaction Of Polymer Filmsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Photoreaction of New Chalcone-Based Side Chain Type Liquid Crystalline Polymers and Alignment Behavior of Liquid Crystal on the Irradiated Films

Mutoh

Tsutsumi

Koide

2002

Polym J

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“…14 The polymers containing chalcone group in the side chain were also frequently studied for application to LC photoalignment layer. 15 The induction mechanism of optical anisotropy is identical with that in polyvinylcinnamate.…”

Section: Introductionmentioning

confidence: 53%

Photo-alignment of Low-molecular Mass Nematic Liquid Crystals on Photochemically Bifunctional Chalcone-epoxy Film by Irradiation of a Linearly Polarized UV Light

Choi

Kwan

2002

Bulletin of the Korean Chemical Society

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Photocrosslinkable chalcone-epoxy compound comprising 1,3-bis-(4-hydroxy-phenyl)-propenone was synthesized for fabricating the photo-alignment layer of liquid crystals. Chalcone group was introduced into the main chain unit of the epoxy oligomer. We observed a photodimerization behavior and an optical anisotropy of this material by irradiation of a linearly polarized UV(LP-UV) light. With a trace amount of cationic photoinitiator (TRS-HFA), polymerization of epoxy groups was also conducted at the similar wavelength range used for photodimerization. Linearly polarized UV irradiation on the chalcone-epoxy films with cationic photoinitiator induced optical anisotropy of the film and the resultant film can be used for alignment layers for low molecular weight nematic liquid crystals.

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