• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.641-644
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• 2009

We demonstrated a solvent-assisted soft-lithographic patterning method for producing patterned structure and patterned ordering with lyotropic liquid crystalline polymer (LCP) film. Experimental results showed that the liquid crystalline ordering of lyotropic film could be controlled by shearing effects of the fluidic solvent though the patterned mold channels. In this work, two types of lyotropic LCPs were used to investigate the effects of the alkyl chain length of the lyotropic LCP on producing liquid crystalline ordering through the solvent-assisted fluidic patterning.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.22-28
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• 1995

Since the discovery of liquid crystallinity by Reinitzer [1] in 1988 as he studied the melting behavior of cholesteryl benzoate, anisotropic structural ordering in fluid phases has been of considerable interest to chemists, physicists and other scientists. Polymers which exhibit liquid crystallinity either in solution (lyotropic) or in the neat state upon heating (thermotropic) have both theoretical and practical importance [2]. Du Pont's Kevlar, a high modulus polyamide fiber spun from a lyotropic solution, is a prime example of such an application.

• The Korean Journal of Rheology
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• v.9 no.4
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• pp.200-205
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• 1997

등방상에서는 폴리파라페닐렌테레프탈아미드(PPD-T)와 히드록시 프로필 셀룰로오 스(HPC)가 비슷한 유변학적 거동을 보였다. 그러나 이방성에서는 네마틱상을 형성하는 PPD-T와 콜레스테릭상(또는 꼬인 네마틱상)을 형성하는 HPC는 상이한 유변학적 특성을 나타냈다. 이방상을 나타내는 임계농도(C*)이상의 농도에서 Herchel-Bulkey 모델에 의해 얻 어진 항복응력을 보면 HPC의 경우 농도에 관계없이 거의 일정한 값을 나타낸 반면PPD-T 의경우에는 농도증가와 더불어 항북응력값이 크게 증가하였다. 또한 PPD-T가 일\ulcorner거으로 HPC보다 큰값의 항복응력을 나타냈다. 진동수 1 rad/s 에서는 PPD-T와 HPCahen 탄성계 수 G＇/2G＂가 농도의 증가와 더불어 증가하엿다. 그러나 100rad/s 에서는 HPCdmlruddn 임계농도이상의 농도에서 농도증가와 더불어 탄성계수값이 단순감소한 반면 PPD-T의 경우 에는 포화농도(B-point)이상의 농도에서 농도증가와 더불어 탄성계수값이 계속적으로 증가 하였다. HPC의 경우 저장탄성률이 변형정도의 영향을 받지 않았으나 PPD-T의 경우에는 저장탄성률이 변형정도에 매우 민감하였다.

• Polymer(Korea)
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• v.24 no.3
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• pp.418-430
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• 2000

A new hydroxylpropyl chitosan (HPCTO) capable of forming both thermotropic and lyotropic liquid crystalline phases was synthesized by reaction of alkali chitosan with propylene oxide and its solid films cross-linked with glyoxal were prepared by casting the liquid crystalline solution in methanol. The thermal and swelling properties of the cross-linked films were investigated. The films displayed fingerprint patterns characteristic of cholesteric liquid-crystalline phase, and their pitches increased with increasing temperature and cross-linker concentration. The cross-linked samples exhibited an anisotropic swelling in both water and methanol, suggesting that the two-dimensional cross-linking preferentially performs between HPCTO molecules. The degree of anisotropy highly depended on the solvent, but hardly on the cross-linker concentration investigated.

• Polymer(Korea)
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• v.36 no.3
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• pp.380-392
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• 2012

Four kinds of N,O-hydroxypropyl chitosans (HPCTOs) with degree of substitution(DS) and molar substitution (MS) ranging from 2.47 to 2.52 and 4.9 to 7.8, respectively were synthesized, and their molecular chracteristics and thermotropic and lyotropic liquid crystalline properties were investigated. MS was exceedingly larger than DS, showing that in the later stages of reaction, propylene oxide was preferentially added to the side chains rather than the main chain. All the derivatives formed thermotropic cholesteric phases. The glass and clearing temperatures were decreased with increasing MS. The optical pitches (${\lambda}_m$'s) of the thermotropic cholesteric phases increased with temperature. However, the ${\lambda}_m$'s of the derivatives at the same temperature increased with increasing MS. Solutions of HPCTOs in water, methanol, ethanol, acetic acid, and formic acid containing more than 30 wt% polymer also formed cholesteic phases whose ${\lambda}_m$'s decreased exponentially with increasing polymer concentration. The concentration dependence of ${\lambda}_m$ of HPCTO solutions, however, highly depended on the nature of the solvent and MS. The thermotropic and lyotropic mesophase properties of HPCTOs were significantly different from those reported for hydroxypropyl celluloses. The results indicate that the secondary amino group in the C-2 position plays an important role on the formation, stabilization, and temperature and concentration dependencies of ${\lambda}_m$ of the cholesteric mesophase.