Pre-tilt angles as a function of polyimide composition for copolyimides

Yokokura, Hisao; Myrvold, Bernt O.; Kondo, K.; Oh-hara, Shuichi

doi:10.1039/jm9940401667

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…In addition to the low curing temperature and light color, the alignment materials applied to LCDs with a large display area, such as the supertwisted nematic‐type (STN) LCD, must achieve a high pretilt angle, which is the angle between the direction of the liquid‐crystal (LC) molecules and the substrate 4. The conventional PI alignment layer can only achieve a small pretilt angle, whereas the introduction of long alkyl groups into the PI structure (as the main chain or side group) has been observed to be effective at increasing the pretilt angle 11, 14, 15, 22, 23…”

Section: Introductionmentioning

confidence: 99%

Preparation and properties of organosoluble, colorless, and high‐pretilt‐angle polyimides based on an alicyclic dianhydride and long‐main‐chain alkyl‐group‐containing diamines

Zhang

Yin

et al. 2001

J of Applied Polymer Sci

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Alicyclic polyimides (PIs) were prepared from 3-carboxylmethyl-cyclopentane-1,2,4-tricarboxylic acid dianhydride and ␣,-di(4-aminophenoxyl)alkanes. These PIs possessed good solubility in aprotic, strongly polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethyl formamide, and m-cresol. They possessed high transparency in visible wavelengths and were almost colorless. The pretilt angle of a liquid-crystal display with these PIs as the alignment layer increased linearly as the length of the alkyloxy groups increased; it was close to 5°for the PI samples PI-10 and PI-12.

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Section: Introductionmentioning

confidence: 99%

Preparation and properties of organosoluble, colorless, and high‐pretilt‐angle polyimides based on an alicyclic dianhydride and long‐main‐chain alkyl‐group‐containing diamines

Zhang

Yin

et al. 2001

J of Applied Polymer Sci

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“…Aromatic polyimide (PI) is a type of high‐performance polymeric material characterized by its outstanding mechanical properties and electrical properties, especially at elevated temperatures, and it has been widely applied in the microelectronics, electrical, and aerospace industries 1–6. One of the major applications of the PI in the microelectronics industry is as the alignment film of liquid‐crystal displays (LCDs) 7–21. However, the application of conventional aromatic PIs in LCDs is somewhat limited by their poor processability, the existence of a brownish color, and the provision of only a small pretilt angle 1–6.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the low curing temperature and optical transparency, the alignment materials applied in LCDs with large display areas, such as supertwisted‐nematic‐type LCDs (STN LCDs), must achieve a high pretilt angle [the angle between the director of the liquid‐crystal (LC) molecules and the substrate] 10. The conventional PI alignment layer can only achieve a small pretilt angle, whereas the introduction of long alkyl groups into the PI (as the main chain or side group) has been found to be effective in increasing the pretilt angle 13, 18–21…”

Section: Introductionmentioning

confidence: 99%

Preparation and properties of high-pretilt-angle polyimides based on an alicyclic dianhydride and long alkyloxy side-group-containing diamines

Li¹,

Yin²,

Sui³

et al. 2000

J. Polym. Sci. A Polym. Chem.

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A series of polyimides were prepared by a solution polycondensation reaction between 3‐carboxylmethylcyclopentane‐1,2,4‐tricarboxylic dianhydride and 4‐alkyloxybenzene‐1,3‐diamines in N‐methyl‐2‐pyrrolidone and chemical imidization with triethylamine and acetic anhydride. These polyimides possess great organo‐solubility, high optical transparency, and high pretilt angles. They are soluble not only in strong polar aprotic organic solvents such as N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide, m‐cresol, and 1,4‐butyrolactone but also in common low‐boiling‐point solvents such as chloroform and tetrahydrofuran, and some are even soluble in acetone. They exhibit high transparency at wavelengths greater than 320 nm. They can generate pretilt angles greater than 5°, and some can even achieve pretilt angles greater than 10°. The pretilt angle of a polyimide increases with the increasing length of the alkyloxy side group. The polyimides possess glass‐transition temperatures between 180 and 230 °C and thermal decomposition temperatures (onset temperatures) of about 435 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1943–1950, 2000

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A novel orientation material for liquid crystals based on modified ladder‐like polysiloxanes

Tang

Cui

Xie

et al. 1997

Macro Chemistry & Physics

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A new orientation material for liquid crystals (LCs) based on modified ladder-like polysiloxanes (LPSs) is investigated. The curing temperature (150-200°C) of these grafted LPSs is much lower than that of the traditionally used polyimides (PIS) (250-300 "C). The pre-tilt angles of a nematic liquid crystal (LC), 4-pentyl-4'-cyanobiphenyl (5CB), are between 2-8", depending on the rubbing conditions and the side chains. Annealing experiments at 100°C and 180°C demonstrated that the stability of these orientation films is quite well.

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Pre-tilt angles as a function of polyimide composition for copolyimides

Cited by 5 publications

References 11 publications

Preparation and properties of organosoluble, colorless, and high‐pretilt‐angle polyimides based on an alicyclic dianhydride and long‐main‐chain alkyl‐group‐containing diamines

Preparation and properties of organosoluble, colorless, and high‐pretilt‐angle polyimides based on an alicyclic dianhydride and long‐main‐chain alkyl‐group‐containing diamines

Preparation and properties of high-pretilt-angle polyimides based on an alicyclic dianhydride and long alkyloxy side-group-containing diamines

A novel orientation material for liquid crystals based on modified ladder‐like polysiloxanes

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