• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.330-332
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• 2008

Banana-shaped molecules were synthesized introducing ester linking group into mesogenic unit, varying the central unit with 1,6-, 2,3-naphthylenes, and introducing the hexyloxy group as the terminal flexible unit. The properties of the compounds were characterized by FT-IR, NMR spectroscopy, DSC, polarizing optical microscopy, and X-ray diffractometry.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.504-508
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• 2003

New banana-shaped achiral compounds, 4-chloro-1,3-phenylene bis [4-4(3-fluoro-9-alkenyloxy) phenyl-iminomethylbenzoate]s and 4-chloro-1,3-phenylene bis [4-4-(3-fluoro-10-alkanyloxy) phenyliminomethyl benzoate]s were synthesized by varying the substituent (X=H, F, or Cl); their electrooptical properties are described. The smectic phases, including a switchable chiral smectic C ($SmC^{\ast}$) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy, and triangular method. The presence of vinyl end group at the terminals of linear side wings in the banana-shaped molecules induced a decrease in melting temperature. The smectic phase having the undecenyloxy group such $as-(CH_2)_9CH=CH_2$ showed ferroelectric switching, and its value of spontaneous polarization on reversal of an applied electric field was 2250 $nC/cm^2$, while the value of spontaneous polarization of the smectic phase having the decanyloxy group such as $-(CH2)_9CH_3$ was 3700 $nC/cm^2$. We could obtain the ferroelectric phase with low isotropic temperature by varying the end group at the terminals of linear side wings in the banana-shaped achiral molecules.

• Bulletin of the Korean Chemical Society
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• 제21권11호
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• pp.1155-1158
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• 2000

• 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.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1171-1176
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• 2004

Three banana-shaped achiral compounds, 4-chloro-1,3-phenylene bis [4-{4-(undecenyloxy)phenyl imino-methyl} benzoate] derivatives, were synthesized with variation of a substituent (x=H, F, Cl); their antiferro-electric properties are described. The smectic mesophases, including a switchable chiral smectic C(Sm $C^{\ast}$) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy, triangular wave method, and X-ray diffractometry. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules induced a decrease in melting temperature and formation of the switchable Sm $C^{\ast}$ phase in the melt. The smectic phase having a lateral fluorine-substituent at 3-position of the Schiff's base moiety showed antiferroelctric switching, and the value of spontaneous polarization on reversal of an applied electric field was 250 nC/$cm^2$ .

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.445-448
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• 2002

New banana-shaped achiral compounds, 1,3-phenylene bis [4-{4-(7-octenyloxy)phenyliminomethyl}benzoate](PBOEB), 1,3-phenylene bis [4-{3-fluoro-4-(7-octenyloxy)phenyliminomethyl}benzoate] (PBFOEB), 1,3-phenylene bis [4-{4-(10-undecyloxy)phenyliminomethyl}benzoate](PBEUB), and 1,3phenylene bis [4-{3-fluoro-4-(10-undecyloxy)phenyliminomethyl}benzoate](PBFEUB) were obtained by general synthetic methods. PBOEB and PBFOEB having the octenyloxy groups such as $-(CH_2)_6CH=CH_2$ showed ferroelectric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/$cm^2$ and 225 nC/$cm^2$, respectively. PBEUB and PBFEUB having the undecyloxy groups such as $-{CH_2)_9CH=CH_2$ showed antiferroelectric switching, and their values of spontaneous polarization on reversal of an applied electric field were 120 nC/$cm^2$ and 140 nC/$cm^2$, respectively. We could obtain ferroelectric and antiferroelectric phases by controlling the number of carbon atom in alkenyloxy chains of bent-core molecules.