• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.49-50
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• 2008

OCB mode has advantages such as fast response time and wide viewing angle. But it has inevitable shortcoming which initial splay state must be changed to bend state. To overcoming this problem, OCB cell filled LC with RM monomer was cured by UV when voltage applied. Through previously mentioned methods, even if electric field is none, bend state was made by stabilized LC director. In this paper, we investigated the electric characteristics of polymer stabilized OCB mode.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.324-326
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• 2008

Novel X-shaped molecules containing perfluoroalkyl alkanes as a side chain have been synthesized and characterized. The properties of mesophases were investigated by a combination of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), X-ray diffractometry (XRD) and electro-optical measurements.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.850-853
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• 2006

Four bent-core compounds were synthesized introducing ester linking group into mesogenic unit, varying the central unit with 1,6-, 1,7-, 2,3-, and 2,7-naphthylenes, and placing the dodecyloxy group in the terminal flexible unit. The structures of four compounds were identified by FT-IR and $^1H$ NMR spectroscopy, and the results were in accordance with expected molecular formula. The mesomorphic properties were investigated by differential scanning calorimetry and polarizing optical microscopy.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.657-660
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• 2009

Optically compensated bend (OCB) mode has intrinsic characteristics such as wide viewing angle and fast response time. However, in order to operate the OCB mode in bend state, this device needs quick transitions from the initial splay state to bend state. In this paper, we proposed OCB mode with initially bend state using reactive mesogen (RM) monomer for surface polymer stabilization. The device shows continuous reorientation of the LC with applied field and a very fast response time.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.

• Textile Coloration and Finishing
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• v.8 no.3
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• pp.1-7
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• 1996

Mesogenic unit를 포함하고 있지 않는 1,4-phenylene diisocyanate, 2,6-bis(5-hydroxypentoxy)naphthalene, 1,4-bis(5-hydroxypentoxy)benzene을 重附加反應을 시킨 結果 生成된 co-polyurethane은 液晶性을 나타내었다. copolyurethane의 熱的 性質과 構造確認을 위하여 DSC, 編光顯微鏡, TG 및 FT-IR, $^{1}$H-NMR로 測定하였다. DSC 測定結果 Tm 및 Ti가 대부분 明確의 나타내었다. 특히 液晶 範圍는 copolyurethane은 homopolyurethane보다 약간 넓은 範圍에서 液晶性을 나타내었다. 예를 들면 copolyurethane(60/40) 및 home-polyurethane(0/100) 의 液晶 範圍는 각각 2$0^{\circ}C$ 및 11$^{\circ}C$이다. 이러한 것은 homopolyurethane이 copiktyretgabe보다 熱的 安定性이 적다는 것을 나타낸다. 그리고 TG의 測定에서도 homopolyurethane(100/0) 및 copolyurethane이 熱的으로 安定하다는 것을 알았다. 예를 들면 homopolyurethane(100/0) 및 copolyurethane(80/20)에서의 5%에서의 TG 測定結果 각각 312$^{\circ}C$ 및 327$^{\circ}C$였다. 이러한 結果는 copolyurethane이 homopolyurethane보다 分子間 水素結合의 影響으로 熱的 安定性을 가져오는 것을 確認 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• v.17 no.11
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• pp.1004-1009
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• 1996

The interactions between a rod-coil liquid crystalline oligomer, ethyl 4-[4'-oxy-4-biphenylcarbonyloxy]-4'-biphenylcarboxylate with poly(ethylene oxide) (DP=12) (12-4) and LiCF3SO3 have been characterized by using Raman spectroscopy. Band assignments were made comparing the spectrum of 12-4 with those of the poly(ethylene glycol) monomethyl ether(PEGME) (Mw=550) and the ethyl-4'-hydroxybiphenyl-4-carboxylate (EHBPC), which are the coil and mesogen analogues, respectively. Analyzing characteristic bands of the 12-4-salt complex, we have found that the bands belonging to the coil and mesogenic units are changed in both intensities and frequencies. The spectral changes were interpreted from the viewpoint of the complexation between 12-4 and the Li+ ion. However, the possibility that the spectral changes in the mesogenic unit are not due to the complexation with the Li+ ion, but due to the conformational changes by the intercalation of nondissociated LiCF3SO3, is not ruled out.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.189-193
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• 1991

A series of compounds that contain varying numbers of the same mesogenic structure, biphenyl p-oxybenzoate unit, attached through a pentamethylene spacer to the central benzene ring were prepared and their liquid crystallinity was studied. The mesophase-forming ability of a dimesogenic compound was found to be greatly dependent on whether or not its geometric shape is linear and also on the existence of the pentamethylene spacer between the mesogen and the central core. The presence of the spacer enhanced the capacity of a compound to form a mesophase. In the trimesogenic compound the mesogens were linked to the 1,3,5-positions of the core benzene ring through the spacer. The compound was found to be enantiotropically nematic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.269-270
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• 2009

The biased vertical alignment (BVA) liquid crystal (LC) mode shows a has a distinct advantage of lower manufacture cost due to the elimination of a lithographic process step to form either ITO-patterning or protrusions on the color-filter substrates. However, those devices have complex voltage conditions which is the respective induce voltage on common electrode, pixel electrode and bias electrode when positive and negative frame. In order to overcome the complex voltage condition, the pretilt angles is controlled by photo polymerization of the UV-curable reactive mesogen (RM). According to our studies, voltages to the cell are critical to achieve an optimized surface-modified quality BVA (Q-BVA) mode which provides the well defined reorientation of the LCs with respect to an electric field.

• Polymer(Korea)
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• v.33 no.5
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• pp.496-500
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• 2009

Optically compensated bend liquid crystal display (OCB-LCD) has many application fields owing to its fast response time and wide viewing angle. However, in order to operate the OCB-LCD in bend state, this device needs quick transitions from the initial splay state to bend state. Unlike conventional approach using transient high voltage for the transition, the OCB-LCD with high surface tilt angle, which was achieved by polymerization of UV curable reactive mesogen monomer under certain voltage, was manufactured and the cell showed bend state initially. Electro-optic and electrical characteristics of the cell were analyzed. The cell shows a fast response time owing to high surface pretilt angle and very low residual DC less than 0.1 V although another polymer layer is formed above polymer alignment layers.