• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.88-90
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• 1994

• Bulletin of the Korean Chemical Society
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• v.18 no.7
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• pp.773-775
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• 1997

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.807-809
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• 1998

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1289-1290
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• 2001

• Fibers and Polymers
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• v.7 no.4
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• pp.358-366
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• 2006

Thermotropic liquid crystal polymer (TLCP)-reinforced poly(butylene terephthalate) (PBT) composites were prepared by melt processing. The improvement in the mechanical properties and the processability of the PBT/TLCP composites was attributed to the reinforcing effect by TLCP phase and its well distribution in the PBT matrix. X-ray diffraction results demonstrated that a slow cooling process leads to the thicker lamellar structures and the formation of more regular crystallites in the composites. The incorporation of TLCP improves not only the tensile strength and flexural modulus but also the heat distortion temperature (HDT) of the PBT/TLCP composites. The HDT values of the composites were dependent on TLCP content. The improvement in the HDT values of the PBT/TLCP composites may be explained in terms with the increased flexural modulus, the development of more regular crystalline structures, and the enhancement of the ability of the composites to sustain the storage modulus by TLCP phase. In addition, the simple additivity rule makes it possible to predict the HDT values of the PBT/TLCP composites.

• Macromolecular Research
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• v.17 no.4
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• pp.271-275
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• 2009

This paper describes the out-of-plane order of a liquid crystalline(LC) methacrylate copolymer(3) comprised of a methacrylate(1) with a 4-styrylpyridine moiety as the photo-cyclodimerizable group and a benzoate moiety as the mesogenic group in the side chain, and another methacrylate(2) with a 4-(4-methoxyphenyl)benzoate moiety as the mesogenic group. The composition of 1 and 2 units in 3 was estimated to have a molar ratio of 54.2:45.8 by $^{1}H$ NMR spectroscopy. The X-ray diffraction study revealed that the copolymer forms a partial bilayer smectic structure. The copolymer gave rise to a high out-of-plane order parameter of about 0.74 in a wide LC temperature range of $110{\sim}160^{\circ}C$ after linearly polarized, UV light irradiation and subsequent annealing. Moreover, the external reflection IR analysis indicated that excess UV-light irradiation makes the out-of-plane LC structure of the copolymer appear in a higher and wider temperature range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1367-1372
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• 2010

Copoly(ether-ether-ester)s having flexible side chain were synthesized by polycondensation. Intrinsic viscosities of polymers were between 0.42 and 0.78dl/g in tetrachloroethane. The polymer structures were investigated by $^1H$-NMR and FT-IR, and thermal and liquid crystalline properties of polymers were measured by DSC, TGA, POM and XRD. As results of investigations, synthetic copolymers exhibited lower melting temperature than homopolymers. When the biphenylene units contents in copolymer were more than 60 mol %, nematic mesophase was observed, and the mesophase of synthetic polymers was dependent upon biphenylene content.

• Polymer(Korea)
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• v.25 no.6
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• pp.876-883
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• 2001

A thermotropic liquid crystalline polyester (TLCP) containing a side group was, synthesized from ethoxyhydroquinone and bromoterephthalic acid. Intercalation of TLCP in layered clays is accomplished by heating the polymer with hexadecyl ammonium-montmorillonite ($C_{16}$) above melting transition temperature ($T_m$). Liquid crystallinity of the TLCP/$C_{16}$-hybrid was observed up to 6 wt% $C_{16}$-MMT. Some of the $C_{16}$-MMTs in TLCP were highly dispersed in a nanometer scale, but some of them were agglomerated. Thermal and morphological properties of the nanocomposites were examined by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), polarized optical microscope, and electron microscopes (SEM and TEM).

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.562-569
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• 2001

A homologous series of new H-shaped twin liquid crystal molecules (PPPA-n) with flexible spacers, oxypolymethyleneoxy, has been prepared by esterification of acid chloride of $\alpha$,$\omega$-bis(2,5-dicar-boxyphenoxy) alkanes with p-phenylphenol. The length of spacer was varied from oxyethyleneoxy (n=2) to oxydecamethyleneoxy (n=10). Their thermodynamic data were measured by differential scanning calorimetry and liquid crystalline properties were investigated by a hot-stage polarizing microscope.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.105-110
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• 2013

Single crystalline $In_xGa_{1-x}As$ nanowires are grown on Si (111) substrate via Vapor-Liquid-Solid growth mode using metal-organic chemical vapor deposition. The ternary nanowires have been grown with various growth conditions and examined by electron microscopy. The alloy compositions of the nanowires has been investigated using Energy-dispersive X-ray spectroscopy. We have found that the composition gradient of the nanowire becomes larger with growth temperature and V/III ratio.