• Proceedings of the Korean Fiber Society Conference
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• 1986.06a
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• pp.13-13
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• 1986

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.473-477
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• 1999

• Electrical & Electronic Materials
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• v.9 no.3
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• pp.265-269
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• 1996

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength and surface order parameter on rubbed polyimide (PI) surfaces. The order of polar anchoring strength for NLCs on rubbed PI surfaces is 5CB > PCH5 > CCH5. From the above results, we suggest that the polar anchoring strength depends on the polarizability of the NLCs. The surface order parameter for NLCs is 5CB > PCH5 > CCH5 on rubbed PI surfaces. We conclude that the polar anchoring strength is strongly related to the surface order parameter on rubbed PI surfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.265-268
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• 1995

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength and surface order parameter on rubbed polyimide (PI) films. The order of polar anchoring strength for NLCs on rubbed PI films is 5CB > PCH5 > CCH5. This order is the same for all rubbing strengths investigated. The surface order parameter for NLCs is 5CB > PCH-5 > CCH5 on rubbed PI films. From these results, we suggest that the polar anchoring strength is strongly related to the surface order parameter.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.90-90
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• 2006

Mesogen-Jacketed Liquid Crystalline Polymers, MJLCPs, are polymers with mesogenic side groups directly attached to main-chains without using flexible connecting spacers and are able to form liquid crystalline structures. Later work on structure-property of the polymers revealed that the side groups are not necessarily mesogenic for the polymers to form a mesophase so long as that the side groups are directly attached to the backbones and the side groups are large enough. Because of its inherent chain stiffness and that the monomers of MJLCPs are readily polymerizable by "living" free radical polymerizations, MJLCP offered a unique handy tool for making block copolymers. In addition, MJLCP offered also new opportunities for novel functional materials.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.414-416
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• 1995

We have studied the effect of the mesogenic core of nematic liquid crystals (NLCs) for polar (out-of-plane tilt) anchoring strength on rubbed polyimide (PI) films. The order of polar anchoring strength for NLCs on rubbed PI films is 5CB > PCH5 > CCH5. This order is the same for all rubbing strengths investigated. From these results, we suggest that the polar anchoring strength strongly depends on the polarizability of the NLCs.

• 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.20 no.12
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• pp.1421-1427
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• 1999

4-Hydroxy-4'-methoxyazobenzene and 4-hydroxy-4'-cyanoazobenzene were synthesized from phenol with p-anisidine and p-aminobenzonitrile through a diazotization reaction, respectively. They were reacted with 2-chloroethanol, 2-(2-chloroethoxy)ethanol, or 2-[2-(2-chloroethoxy)ethoxy]ethanol to produce six kinds of new mesogenic alcohols having an azobenzene group that is sensitive to the ultraviolet. Twelve kinds of new photoresponsive monomers with two symmetrical mesogens were prepared by the reaction of the mesogenic alcohols with fumaric acid or maleic acid through a Mitsunobu reaction. The resulting monomers have different length of flexible ethyleneoxy spacer tethered to azobenzene group. The length of the spacer affected their thermal stability, solubility, and phase transition temperature. Structures of the monomers were identified by FT-IR and ¹H-NMR spectra. Their phase transition temperatures and thermal stability were also investigated by a differential scanning calorimetry (DSC) and a thermogravimetric analysis (TGA). From an optical polarizing microscopy, all the prepared monomers except fumarate-1 and maleate-1 were found to show enantiotropic liquid crystallinity with a smectic texture like focal-conic, fan-shaped, and batonnet textures.

• Bulletin of the Korean Chemical Society
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• v.7 no.5
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• pp.353-357
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• 1986

Mutual miscibility between thermotropic, nematic compounds with two terminal mesogenic units and a central spacer was studied by differential scanning calorimetry (DSC) and on a polarizing microscope. It was found that the isomorphous, nematic dimesogenic compounds with wide variety of structures are miscible in mesophases with each other over the whole range of composition and that Schroder-van Laar equation almost correctly predicts the melting temperature and composition of eutectic mixtures. There was a pair of compounds which were exceptional and did not form a eutectic mixture and, instead, revealed a monotonous change in melting (T$_{m}$) and isotropic transition temperatures (T$_{i}$) as the composition of the mixture was varied. The compounds were of almost same structure in shape and seemed to undergo formation of solid solution.