• Polymer Science and Technology
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• v.5 no.3
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• pp.254-264
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• 1994

• Polymer Science and Technology
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• v.2 no.6
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• pp.438-452
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• 1991

• Polymer(Korea)
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• v.24 no.1
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• pp.113-123
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• 2000

Poly(p-hydroxybenzoate) (PHB)/poly(ethylene terephthalate) (PET) 8/2 thermotropic liquid crystalline copolyester, poly(ethylene 2,6-naphthalate) (PEN) and PET were mechanically blended to obtain the pseudo liquid crystalline (LC) phase of ternary blends. The torque values of blends with increasing PHB content were abruptly decreased above 40 wt% of PHB content, because the melt viscosity of ternary blends decreased. Tensile strength and initial modulus of blends containing above 30 wt% PHB were improved with increasing PHB content. Tensile strength and modulus of fiber were increased with PHB contents and take-up speed. Degree of transesterification and randomness of blends were increased with blending time. The blend of 40 wt% PHB was shown pseudo LC phase in the polarized optical photographs. Crystallinity of PHB/PEN/PET ternary blend were increased with PHB content.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.933-935
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• 2002

In this paper, new non-chiral molecules with semi-fluorinated alkyl chains were synthesized varying the structure of central bent core unit. Their mesomorphic properties were investigated by DSC and polarized microscopy. The compound with 1,3-dihydroxy phenylene unit could form an enantiomeric smectic phase, but the remaining compounds with bent-core mesogenic unit were not liquid crystalline. In this presentation, their x-ray measurement and electro-optical property will be also described.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.464-473
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• 1993

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.873-876
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• 2004

New Oligothiophene derivatives having liquid crystalline property have been designed, synthesized and characterized. New oligothiophene derivatives were prepared by a palladium-catalyzed cross-coupling reaction via zinc-substituted thiophene. The structures of materials were characterized by various spectroscopies. The new obtained oligothiophene derivatives showed high thermal stability above 300 $^{\circ}C$ and exhibited several transition temperatures, evidence of mesophase. In field-effect transistors, a charge carrier mobility of 1.9 x $10^{-2}$ $cm^2$/Vs was observed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.559-566
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• 2006

The isothermal crystallization behavior of blends of poly(ethylene terephthalate) and liquid crystalline polymers(LCP) was studied. The Avrami analyses were applied to obtain the information on the crystal growth geometry and factors controlling the rate of crystallization. The crystallization kinetics for the blends followed the classical Avrami equation up to a high degree of crystallization regardless of crystallization temperature, The values of Avrami exponent, n, for PET in the blends were estimated to be around 2, which indicate that the polymer crystals grow into one-dimensional linear or fiber-like crystallization mode. The crystallization rate, as expected, decreases with increasing the crystallization temperature.

• Bulletin of the Korean Chemical Society
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• v.27 no.1
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• pp.39-43
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• 2006

The relaxed torsional potential of a liquid crystalline polymer containing an ester functional group in a mesogenic unit (hereafter 12-4 oligomer) has been calculated with the ab initio self-consistent-field using 6-31G$^*$ basis set. GIAO^{13}C NMR chemical shifts also have been calculated at the B3LYP/6-31G$^*$ level of theory for each conformational structure obtained from torsional potential calculation. The results show that the phenyl ring-ester linkages are coplanar with the dihedral angle of about 0$^{\circ}$ and the ring-ring linkages in the biphenyl groups are tilted with the dihedral angle of around 43-44$^{\circ}$ in the lowest energy conformer. The biphenyl ring has a comparatively lower energy barrier of internal rotation potential in the ring-ring than that of phenyl ring-ester. The ^{13}C chemical shifts of carbonyl carbons were found to move to upfield due to $\pi$ -conjugation with phenyl ring and slightly affected about 0.5 ppm by dihedral angle of the ring-ring linkage.

• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.32-35
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• 1997

Aggregation states ans electro-optic properties of a binary mixture by mixing a side chain type liquid crystalline polymer(LCP) and a low molecular weight liquid crystal(LMLC) have been studied. Side chain liquid crystalline polysiloxanes were synthesized from allyl bromide, p-hydroxy benzoic acid, p-cyanophenol, p-methoxyphenol and polysiloxanes. Low molecular weight liquid crystals were synthesized from allyl bromide, p-hydroxy benzoic acid and 4-cyano 4'-hydroxy biphenyl. And then, their properties were compared with blended liquid crystals. The thermal properties of the blended liquid crystals were evaluated using differential scanning calorimetry. The phase behavior of blended sample with temperature were also observed polarized microscope with hot stage. Thus, it seemed to us that a study of LC polysiloxanes with LMLC would be useful, especially in view of the fact that, systematic investigations have been carried out on the effects of changes in LCP/LMLC binary system on the properties of this relatively new type of liquid crystal.

• Polymer(Korea)
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• v.31 no.1
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• pp.37-46
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• 2007

Fully or nearly fully 6- [4- (4'- (nitrophenylazo)phenoxycarbonyl)]pentanoated polysaccharide derivatives were synthesized by reacting cellulose, amylose, chitosan, chitin, alginic acid, pullulan or amylopectin with 6- [4- (4'- (nitrophenylazo)phenoxy) ] pentanoyl chloride (NA6C) and their thermotropic liquid crystalline behaviors were investigated. Like in the case of NA6C, all the polysaccharide derivatives formed monotropic nematic phases, suggesting that the mesophase structure of the polysaccharide derivatives is dertermined by the mesogenic side groups and not by the polysaccharide backbone. This is the first report of polysaccharide derivatives, except cellulose derivative, that form thermotropic nematic phases. The thermal stability and degree of order of the nematic phases observed for poly saccharide derivatives were significantly different from those reported for the polymers in which the azobenzene groups are attached to flexible or rigid backbones through flexible spacers. The results were discussed in terms of the difference in the arrangement of the main and side chains and the flexibility of the main chain.