• Korean Chemical Engineering Research
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• 제43권1호
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• pp.176-180
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• 2005

방향족 Schiff base 메소제닉 단위와 폴리메틸렌 유연격자로 이루어진 한 계열의 주사슬 액정중합체와 네 계열 화합물의 액정성을 살펴보았다. 이들의 열적 성질과 액정성은 시차 주사 열분석기와 가열판이 부착된 편광현미경에 의하여 조사하였다. 중합체와 화합물 액정상의 성질은 중앙 폴리메틸렌 유연격자와 말단 알콕시기의 길이에 크게 의존하였다. 중합체 I과 계열 III 화합물은 녹는점과 등방성액체화 전이온도에서 짝수-홀수 효과를 보여 주었으나 계열 II와 IV 화합물은 등방성액체화 전이온도에서만 짝수-홀수 효과를 나타내었다. 편광현미경을 통하여 이들의 광학구조를 관찰하였을 때 네마틱과 스멕틱 액정상을 형성하였다.

• Bulletin of the Korean Chemical Society
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• 제11권3호
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• pp.209-214
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• 1990

A series of compounds consisting of 4'-oxybenzylidene-4-n-butylaniline, a mesogen, and a p-substituted phenoxyterephthaloyl structure a non-mesogen, interconnected through a central hexamethylene spacer were synthesized and their thermal behavior and liquid crystallinity were studied. p-Substituents included in this study are H, Cl, CN, $NO_2,\;n-C_4H_9O$ and phenyl groups. The compounds having phenyl and $n-C_4H_9O$ substituents are enantiotropic and form smectic-A(SA) and nematic (N) phases. The compound with $NO_2$ substituent is monotropic and forms only a nematic phase on heating the solid, whereas it forms nematic as well as $S_A$ phases on cooling the isotropic liquid. The rest compounds were found to be non-liquid crystalline. This is in great contrast to the fact that the monomesogenic model compound 4'-n-hexyloxybenzylidine-4-n-butylaniline forms $S_B,\;S_C,\;S_A$ and N phases enantiotropically.

• 대한화학회지
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• 제54권1호
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• pp.169-173
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• 2010

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.274-278
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• 2003

New banana-shaped achiral compounds, 1,3-phenylene bis [4-{4-(alkenyloxy) phenyliminomethyl}benzoate]s were synthesized by varying the length of alkenyl group; their ferroelectric properties are described. The smectic mesophases, including a switchable chiral smectic C $(Sm\;C^*)$ phase, were characterized by differential scanning calorimetry, polarizing optical microscopy and triangular wave method. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules containing Schiff's base mesogen induced a decrease in melting temperature and formation of the switchable $(Sm\;C^*)$ phase in the melt. The smectic phases having the octenyloxy group such as $(CH_2)_6CH=CH_2$ showed ferroelctric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/cm² (X=H) and 225 nC/ cm² (X=F), respectively. We could obtain ferroelectric phases by controlling the number of carbon atom in alkenyloxy chain of a bent-core molecule.