• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.242-243
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• 2006

In this work, we report the synthesis and characterization of azomethineester polymers that consist of banana-shaped mesogen in their backbone. Two parts of the key structure of five-ring bent-core mesogen were modified by connecting different angle of central unit (Ar), and introducing lateral substituent into the outer ring (X). The synthetic details includes (1) placing the dioxydodecamethylene unit as a flexible spacer, (2) possessing 2,3- or 2,7-naphthylene, or 1,2-phenylene connection on the central unit, and (3) introducing fluorine or chlorine substituent (X = F or Cl) into the outer phenylene unit.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.171-174
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• 2006

In this work, we report the synthesis and characterization of azomethine-ester polymers that consist of banana-shaped mesogen in their backbone. Two parts of the key structure of five-ring bent-core mesogen were modified by connecting different angle of central unit (Ar), and introducing lateral substituent into the outer ring (X). The synthetic details includes (1) placing the dioxydodecamethylene unit as a flexible spacer, (2) possessing 2,3- or 2,7-naphthylene, or 1,2-phenylene connection on the central unit, and (3) introducing fluorine or chlorine substituent (X = F or Cl) into the outer phenylene unit.

• Elastomers and Composites
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• v.40 no.3
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• pp.212-221
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• 2005

Polyurethanes containing mesogen unit (MPU-6) were prepared from 4,4'-diphenylmethane diisocyanate (MDI) and 4,4'-bis(6-hydroxy hexoxy)biphenyl (BP-6) having flexible chain composed of 6 carbons. Intrinsic viscosities of MPU-6s were in the range of $0.23{\sim}0.56 dL/g$. The mesomorphic behaviors of MPU-6 were observed in X-ray and polarizing microscopy analysis. However, MPU-6s demonstrated a 'virtual liquid crystal' behavior, which did not exhibit mesophase on slow heating and slow cooling. MPU-6 having lower molecular weight exhibited higher crystallization rate and melting crystallization temperature due to increased mobility of polymer chains. The increased mobility of polymer chains facilitate the orientation of mesogen units that may act as a nucleating agent.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.799-806
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• 2016

We present a polarization-dependent prism array film for controlling the viewing angle distribution of liquid crystal (LC) display panels without loss of light efficiency. On a directional backlight unit, our polarization-dependent prism array film, made into a stacked bilayer with a well-aligned liquid crystalline reactive mesogen (RM) layer on the UV-imprinted prism structure, can continuously control the light refraction function of the prism array by electrically switching incident polarization states of a polarization-controlling layer prepared by a twisted nematic LC mode. The viewing angle control properties of the polarization-dependent prism array film are analyzed under different prism angle and refractive index conditions of the RM layer. A simple analytic model is also presented to describe the intermediate viewing angle distributions with continuously varying applied voltages and incident polarization states.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1201-1210
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• 2002

A new series of hyperbranched aromatic polyesters containing azoxybenzene mesogens and polymethylene spacers were prepared by polymerizing AB2 type monomers that have the isophthaloyl dicarboxylic acid terminal at one end and the p-oxyp henol terminal at the other end. The monomers contain a built-in azoxybenzene mesogen that is linked to the terminal groups through polymethylene spacers. The polyesters prepared were characterized by solution viscosity, differential scanning calorimetry, X-ray diffractometry and polarizing microscopy. All of the polyesters were found to be thermotropic (nematic). Their glass-transition temperatures and mesophase temperature ranges were very sensitive to the length of the two spacers existing in the repeating unit. The degree of branching of one of the polyesters was determined by the NMR spectroscopy and found to be 0.56.

• 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.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.339-346
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• 1997

Liquid crystalline polyurethanes were prepared from 1,4-bis(6-hydroxyhexoxy)benzene (BHB6) and 2,5-tolylene diisocyanate (2,5-TDI) solution polymerization in dimethylformamide produced intrinsic viscosities in the range 0.26 and $0.42d{\ell}/g$. The polyurethanes were investigated by DSC, Polarizing microscopy, X-ray, $^1H$-NMR and IR spectroscopy. Polyurethanes of two different molecular weights were studied in detail and these will be referred to as low molecular weight and high molecular weight. Polyurethane 2,5-TDI/BHB6 with $[{\eta}]=0.26d{\ell}/g$ prepared from BHB6 and 2,5-TDI, exhibited monotropic liquid crystallinity, although these polyurethanes contained no mesogenic core unit. For example, LCPU-L(low molecular weight) exhibited $T_{I-LC}$ of $122^{\circ}C$ $T_{LC-K}$ $89^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.197-199
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• 2007

Four banana-shaped compounds have beene synthesized introducing ester linking group into mesogenic unit, varying the central core with 1,6-, 1,7-, 2,3-, and 2,7-naphthylene units, and introducing the dodecyloxy group as the terminal flexible unit. All obtained compounds except one with 1,7-naphthylene unit were reversibly thermotropically liquid crystalline. The compound with 1,7-naphthylene unit could not form the mesophase due to its asymmetrical and sharp substitution angle. The compounds with 1,6- and 2,3-naphthylene units showed an antiferroelectric switchable smectic phase, which has been designated B2 phase. Interestingly, the compound with the 2,3-naphthylene unit showed the two mesophases of B2 and nematic phase.

• 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.

• Textile Coloration and Finishing
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• v.2 no.4
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• pp.245-250
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• 1990

Copolyspiroacetals were synthesized by interfacial polycondensation from 3, 9-bis(4-hydroxyphenyl)-2, 4, 8, 10-tetraoxaspiroundecane(SAB) and 4, 4'-biphenol(BP) with sebacoyl chloride. These copolymers were soluble in polar solvent such as phenol/tetrachloroethane and sulfuric acid, and exibited good thermal stability. But they did not exhibit thermotropic mesophases. The structures of spiroacetal moiety were observed by computer-aided-modeling that had two types of conformational isomers and not linear and/or not planar conformations.