Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Yang, Bo-Na; Shin, Dong-Myung

doi:10.1080/15421406.2014.935973

Cited by 7 publications

(4 citation statements)

References 17 publications

(13 reference statements)

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“…It could be clearly observed that the PI alignments layers derived from APAB exhibited good alignment ability to LC molecules. It has been found in the literature that the LPUV-induced cleavage of main polymer chain in photosensitive CBDA-PIs is responsible for the formation of the easy orientation axis in PI alignment layers 49. As expected, uniform alignment of LC molecules were achieved by PI-I a and PI-II a (Figure7A,C); however relatively inferior alignment was observed for PI-I b derived from BPTP.…”

supporting

confidence: 76%

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

Zhi

Wang²,

Jia³

et al. 2022

Polymers for Advanced Techs

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Poly(amic acid)s (PAAs) alignment agents have been prepared from the alicyclic dianhydrides, including 1,2,3,4‐cyclobutanetetracarboxylic dianhydride (CBDA, I), 1,3‐dimethyl‐1,2,3,4‐cyclobutanetetracarboxylic dianhydride (DMCBDA, II), and ester‐linked aromatic diamines, including 4‐aminophenyl‐4′‐aminobenzoate (APAB, a) and bis(4‐aminophenyl)terephthalate (BPTP, b), respectively. The derived PAAs, including PAA‐Ia (CBDA‐APAB), PAA‐Ib (CBDA‐BPTP), and PAA‐IIa (DMCBDA‐APAB) exhibited the preferable molecular weights, while the PAA‐IIb (DMCBDA‐BPTP) showed the low one due to the low polymerization reactivity both for the DMCBDA dianhydride and the BPTP diamine. All the PAA solutions except PAA‐IIb were adopted as the alignment components to fabricate liquid crystal (LC) minicells with a mode of in‐plane switching (IPS). The polyimides (PI) alignment layers derived from the thermal dehydration reaction of the PAA precursors at 230°C for 30 min showed good alignments effects to the LC molecules, which exhibited the pretilt angles (θp) from 0.09 to 0.15° after being exposed by the linear polarized ultraviolet light sources with the wavelength of 254 nm. In addition, the PI alignment layers afforded good optoelectronic features to the minicells, including the voltage holding ratio values over 97% at room temperature, and the residual direct circuit voltages lower than 1.0 V. The anchoring energy results indicated that the PI‐IIa (DMCBDA‐APAB) alignment layer showed the highest interaction with the LC molecules, and thus exhibited the highest threshold voltage (Vth) in the voltage‐transmittance (V‐T) measurements for the minicells.

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supporting

confidence: 76%

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

Zhi

Wang²,

Jia³

et al. 2022

Polymers for Advanced Techs

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“…[15][16][17]27,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81] Third is polyimide undergoing photodecomposition. [82][83][84] Moreover, polyimide-based photoalignment layers can be designed with a photoreactive group as a side chain or a backbone structure, and polyimide itself can induce…”

Section: Introductionmentioning

confidence: 99%

“…Second is photodimerization caused by cinnamate, coumarin, and chalcone 15–17,27,62–81 . Third is polyimide undergoing photodecomposition 82–84 . Moreover, polyimide‐based photoalignment layers can be designed with a photoreactive group as a side chain or a backbone structure, and polyimide itself can induce photoalignment property.…”

Section: Introductionmentioning

confidence: 99%

Photo‐isomerization, photodimerization, and photodegradation polyimides for a liquid crystal alignment layer

Sugiyama

Sato

Nagai

2022

Polymers for Advanced Techs

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We review the important features of LC orientation for the alignment layer, namely, production method, alignment mechanisms, and required properties. Photoalignment, which could eliminate the disadvantages of the rubbing method is explored. Applicable materials and techniques for photoalignment are also examined. Many materials for photoalignment layers have been proposed, but polyimide‐based materials are commonly used because of their transparency and insulation properties, which are needed for optical electronic devices. Furthermore, photoisomerization, photodimerization, and photodecomposition as photoalignment methods are reviewed, and specific photoreactive groups and alignment mechanisms are used to induce LC alignment. In summary, polyimides cause photodecomposition and have the following disadvantages; (1) requirement of relatively short‐wavelength ultraviolet (UV) irradiation, (2) difficulty in reorienting polymer chains owing to their rigid polymer matrix, and (3) low‐photo reactivities. The solutions for each disadvantage are already proposed, but the required properties should be determined during material design. Polyimide‐based materials introduced with the azobenzene and cinnamate groups are proposed and found to have the ability of fulfilling the required properties. The mechanism of polyimide photodecomposition is not fully understood. It likely has the advantage in terms of LC alignment stability because of the absence of E/Z isomerization. Therefore, the alignment mechanism and availabilities should be further explored.

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“…Most of the PI alignment layers possess the semi-alicyclic structure due to the good comprehensive properties mentioned above. Various PAAs derived from alicyclic dianhydrides, such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and aromatic diamines have been successfully developed for high performance alignment layers [26,27]. By contrast, the varieties of imidized PI components for alignment layers development are quite limited due to the very limited commercially available alicyclic dianhydrides.…”

mentioning

confidence: 99%

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

Zhi¹,

Bi²,

Liu³

et al. 2019

Express Polym. Lett.

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Polyimide (PI) represents a class of high performance heteroaromatic polymers characterized by excellent thermal and environmental stability, high mechanical and dielectric properties as well as flexible molecular structure designability [1-3]. Various functionalities have been achieved for PIs via elaborate combination of specific dianhydride and diamine monomers so as to meet the property demands of high-tech applications [4-6]. Among the various functional PIs, semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines proved to possess the best combined properties considering the polymerization reactivity and the acidity/basicity of the starting monomers [7]. Thus, such kinds of semi-alicyclic PIs usually exhibited superior thermal and mechanical properties, and higher molecular weights to their analogous PIs derived from aromatic dianhydrides and alicyclic diamines or from both of alicyclic dianhydride and diamines [8]. Good comprehensive properties of semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines make them much attractive in optoelectronic fields in recent years [9-11]. The successful 923

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Photo-Alignment Using Benzophenone Sensitized Photodecomposition of the Polyimide

Cited by 7 publications

References 17 publications

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

Photo‐isomerization, photodimerization, and photodegradation polyimides for a liquid crystal alignment layer

Synthesis and characterization of soluble ester-containing polyimide alignment layers with high voltage holding ratio features and potential applications in TFT-LCDs

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