• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.731-735
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• 2002

Electro-optical (EO) performances for the twisted-nematic (TN)-liquid crystal display (LCD) photoaligned with linearly polarized UV exposure on the poly［4- (fluorocinnamate) phenylmaleimide](PFCPMI) surfaces using a new photodimerization method were investigated. For a new UVLPH (UV linearly polarized during heating) photodimerization method, the photopolymer layers were exposed by linearly polarized UV dichroic polarizer without a specific UV filter during heating at $150^{\circ}C$. The Voltage-transmittance (V-T) curve without backflow bounce in the photoaligned TN-LCD with UV exposure on the PFCPMI surface for 10 min using the UVLPH photodimerization method was observed. For response time measurement, the transmittance characteristics of the photoaligned TN-LCD using the UVLPH photodimerization method on the photopolymer surface was better than that of the photoaligned TN-LCD using the UVLP photodimerization method under a room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.4
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• pp.341-344
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• 2001

We synthesized a photo-crosslinkable polymide (polymide (PI)-chalcone-biphenyl (BP)) based polymer and control of pretilt angle for a nematic liquid crystal (NLC) using two kinds of the photodimerization methods by polarized UV exposure the photopolymer surfaces was studied. Pretilt angle of the NLCs using a conventional photodimerization method could be varied between 0$^{\circ}$ and 3$^{\circ}$, by controlling the condition of UV exposure. Pretilt angle of the NLCs using the conventional photodimerization method was higher than a in-situ photodimerization method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.951-954
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• 2001

We investigated the aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various photopolymer surfaces. High Pretilt angle of the NLC can be measured by obliquely polarized UV exposure of 30$^{\circ}$on a photo-crosslinkable polyimide (PI) based polymer surface for 3 min. The pretilt angle of the NLC generated on the photopolymer surface using the in-situ photodimerization method was higher than that of a blending photopolymers (PI and cinnamate materials).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.350-353
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• 2001

Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various photo-crosslinkable polyimide (PI) based polymer and blending photopolymer surfaces were stuided. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyirnide based polymer surface containing biphenyl (BP), decyl (de), and cholesteryl (chol) group, respectively, However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (PI and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.350-353
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• 2001

Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various Photo-crosslinkable polyimide (PI) based Polymer and blending photopolymer surfaces were studied. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyimide based polymer surface containing biphenyl (BP), decal (de), and cholesterol (chol) group, respectively. However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (PI and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.917-921
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• 2001

Aligning capabilities for nematic liquid crystal (NLC) using a in-situ photodimerization method on various Photo-crosslinkable Polyimide (Pl) based polymer and blending photopolymer surfaces were investigated. High pretilt angle of the NLC can be measured by obliquely polarized UV exposure on a photo-crosslinkable polyimide based polymer surface containing biphenyl (BP), decyl (de), and cholesteryl (chol) group, respectively. However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the blending photopolymer (Pl and cinnamate materials) surfaces. Consequently, the pretilt angle of the NLC generated on the photo-crosslinkable polyimide based polymer surfaces using the in-situ photodimerization method was higher than that of the blending photopolymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.4
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• pp.336-340
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• 2001

We have investigated the generation of pretilt angle and alignment stability for a nematic liquid crystal (NLC) with obliquely polarized UV exposure on the three kinds of photo-polymer. High pretilt angle of the NLC was obtained by polarized UV exposure on a PM4Ch surface for 1 min. But, the low pretilt angle of he NLC on a PVCi surface was observed. The pretilt angle generated is attributed ot the photosensitivity by the long side chaining of photo-polymer. Also, a good thermal stability of the three kinds of photo-polymer were obtained by thermogravimetric analysis (TGA) measurement until 300$^{\circ}C$. Finally, the good LC aligning capabilities using the photodimerization method were observed by annealing-treatment until 150$^{\circ}C$.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.133-137
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• 2001

In this research, we synthesized various photo-crosslinkable polyimide based polymers. The control of pretilt angles for a nematic liquid crystal (NLC) using the photodimerization method on the photopolymers was studied. A good thermal stability of the photopolymers was measured by thermogravimetric analysis (TGA) measurement until 450C. High pretilt angles of the NLC were otained by polarized UV exposure on the photopolymers containing biphenyl (BP), decyl (de), and cholesteryl (chal) groups, respectively. However, low pretilt angles of the NLC were measured by polarized UV exposure on the photopolymers containing fluorine and chalcone groups. The high NLC pretilt angles generated are attributable to the biphenyl and alkyl moieties, and the photodimerized chalocone group of the photopolymers. Additionally, good voltage-transmittance and response time characteristics were observed by UV exposure on the photopolymers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.7
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• pp.595-599
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• 2001

The mechanisms of pretilt angle generation for a nematic liquid cystal (NLC) using a photodimerization method with obliquely polarized UV exposure on the various new photo-crosslinkable polymer were studied. A good thermal stability of all the photo-crosslinkable polymers was obtained by thermogravimetric analysis (TGA) measurement until 450$\^{C}$. High pretilt angle of the NLC was observed by polarized UV exposure on the three kinds of the photo-crosslinkable polymers containing biphenyl(BP), decyl(de), and cholesteryl(chol) group, respectively. However, the low pretilt angle of the NLC was measured by obliquely polarized UV exposure on the two kinds of the photo-crosslinkable polymers containing fluorine and chalcone group. Consequently, the high NLC angle generated is attributable to the biphenyl and alkyl moieties, and photo-dimerized chalcone group of the photopolymer.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.137-140
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• 2000

Synthesis of a new copoly (M4Ch-ChMA), copoly ((4-methacryloyloxy) chalcone-cholestery methacrylate), with chalconyl and cholesterol moiety characteristics for photoalignment materials was investigated. Good thermal stabilities of the synthesized copolymers are confirmed by thermogravimetric analysis (TGA) measurement. The pretilt angles of the nematic liquid crystal (NLC) are reduced as UV exposure time is increased on the copolymer surfaces. A pretilt angle of 81$^{\circ}$in NLC was observed with UV exposure of 3 min on the copolymer-3 surface. The NLCs pretilt angle is attributable to increased chalcone with increasing the UV exposure time.