• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.161-162
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• 2003

The synthesis and properties of aromatic polyesters have been extensively studied recently following the observation of the excellent physical and mechanical properties of thermotropic aromatic polyesters noted in both academia and industry$\^$1∼3/. Most aromatic polyesters are composed entirely of rigid, linear, aromatic ester units and as a result, they have high melting temperatures. (omitted)

• Bulletin of the Korean Chemical Society
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• 제23권9호
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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.

• 폴리머
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• 제29권6호
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• pp.523-535
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• 2005

선형 방향족 폴리에스테르는 열방성 액정중합체의 대표적 예로 지금까지 그 구조-액정성 관계가 많이 연구되었다. 본 논문에서는 지난 4반세기 동안 본 연구진이 행한 연구결과를 중심으로 액정성 전방향족 폴리에스테르의 열적특성 및 액정성을 그 화학구조와 관련지어 논의한다. 특히 미세화학구조의 변경이 어떻게 액정성에 영향을 주는가에 논의의 초점을 두었다. 특히 선형구조에서 크게 벗어나는 복합형 액정성 폴리에스테르 및 액정성 고차가지구조 폴리에스테르도 조감하였다. 고차가지구조 고분자는 덴드리머와 관련하여 많은 관심을 끌고 있다. 이 고분자들의 합성법도 말미에 소개하고 있다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1999년도 가을 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.21-24
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• 1999

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1999년도 가을 한국섬유공학회 학술발표회 논문집(Proceedings of the Korean Textile Conference)
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• pp.373-376
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• 1999

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1986년도 학술발표초록집
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• pp.13-13
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• 1986

• Macromolecular Research
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• 제8권1호
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• pp.12-18
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• 2000

Six aromatic polyesters with ether-linkages were prepared from 4,4'-oxybis(benzoic acid) and naphthalenediol (ND) isomers which were 1,4-, 1,5-, 1,6-, 2,3-, 2,6- and 2,7-derivatives. The solution viscosity numbers ranged from 0.23 to 0.65 dL/g. The glass transition temperatures ranged from 142 to 179$\^{C}$. The initial decomposition temperatures were all above 400$\^{C}$, and the residue weights at 600$\^{C}$ were in the range of 50-64%. Only the polyesters derived from 1,5- and 2,6-NDs, which have a linear linking mode, were found to be semicrystalline and could form thermotropically nematic phase. Multiple melting phenomena and annealing of the polyester derived from 1,5-ND and related polymers are described. The experimental results show that the polyester derived from 1,4-ND of linear shape was amorphous and non-liquid crystalline. Particularly, the polyester derived from 2,3-ND could form a smectic mesophase as banana-shaped molecules, and this is ascribed to the C/sub_2v/ symmetry where highly kinked molecules are packed in the same direction.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1997년도 춘계학술발표회 논문집
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• pp.328-332
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• 1997

Hot stretching focused on the improvement of properties of poly(L-lactic acid) fiber. Some aliphatic polyesters are biodegradable under microbial attack and the new unique applications are expected. Generally, these materials have a somewhat low melting temperature and low mechanical properties compared with the aromatic polyesters. In this study, melt-spinning of poly(L-lactic acid) was conducted. We investigated effects of the stretching and the molecular orientation of aliphatic polyester fibers on the change of fine-structure. Glass transition temperature, molecular orientation and crystallinity increased according to the increase of stretching ratio.

• 폴리머
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• 제35권2호
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• pp.176-182
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• 2011

방향족 액정 폴리에스테르는 열방성 액정 중합체의 대표저인 예로 지금까지 구조-물성 관계가 많이 연구되었다. 본 연구에서는 유기 용매에 녹일 수 있는 가용성 방향족 액정 폴리에스테르를 합성하고, 아세틸렌 말단기를 갖는 열경화성 수지와 복합화하여 제반 물성을 비교하였다. 가용성 방향족 액정 폴리에스테르는 6-hydroxy-2-naphthoic acid, terephthalic acid, isophthalic acid 및 4-aminophenol을 단량체로 하여 에스테르 및 아미드 교환 반응에 기초로 한 축합 중합법을 이용하여 합성하였다. 아세틸렌 말단기를 갖는 열경화성 수지는 4-ethynylaniline과 terephthaloyl dichloride, isophthaloyl clichloride, 4,4'-biphenyldicarbonyl dichloride 등과 각각 반응시켜 합성하였다. 가용성 방향족 액정 폴리에스테르와 열경화성 수지를 용액 블렌딩하고 열처리하여 복합체를 제조하였으며, 복합체의 열적 안정성, 열팽창계수, 유전특성 등을 조사하였다.

• Macromolecular Research
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• 제12권2호
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.