Browsing by Author "HSU, CS"

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FLUORINATED DIPHENYL-DIACETYLENE AND TOLANE LIQUID-CRYSTALS WITH LOW THRESHOLD VOLTAGE
(1992-11-09)
WU, ST
;
HSU, CS
;
CHEN, YN
;
WANG, SR
;
應用化學系
Several new fluoro-alkoxy and alkenyloxy (alkoxy with a carbon-carbon double bond) diphenyl-diacetylene and tolane liquid crystals are synthesized and their physical properties evaluated. Double bond position is found to make a pronounced effect on elastic constant, phase transition temperature and heat fusion enthalpy, but little change on birefringence, dielectric anisotropy, and viscosity. These compounds exhibit a high birefringence, low viscosity, and low threshold voltage, and are particularly attractive for infrared light valves and polymer-dispersed liquid crystal displays.
FLUORODIPHENYLDIACETYLENE AND TOLANE LIQUID-CRYSTALS FOR DISPLAY APPLICATION
(1993-08-01)
WU, ST
;
HSU, CS
;
CHEN, YN
;
WANG, SR
;
LUNG, SH
Several fluorinated diphenyldiacetylene and tolane liquid crystals are synthesized and their physical properties evaluated. These liquid crystals exhibit a high resistivity, high birefringence, low viscosity, and modest dielectric anisotropy. Some difluoro compounds show a relatively low melting temperature and small heat fusion enthalpy and are useful for formulating eutectic mixtures. The mixtures consisting of these fluorinated compounds are particularly useful for active matrix, photoactivated light valve, and polymer-dispersed liquid crystal displays.
GAS PERMEATION THROUGH A SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANE-BASED MEMBRANE
(1991-09-01)
CHEN, DS
;
HSIUE, GH
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
A membrane was prepared by sandwiching the side-chain liquid-crystalline polysiloxane (LCP) 3 between two porous poly(propylene) (Celgard) films. Permeation properties for H-2, O2, N2, CH4 and CO2 through the side-chain LCP-based membrane was measured using a gas-chromatographic method at several different temperatures corresponding to the different states of of the side-chain LCP. The gas permeation behaviour depends strongly on the different states of the side-chain LCP. The plots of permeability versus reciprocal temperature show an abrupt change of the slope in the vicinity of the glass transition temperature (T(g)) of the side-chain LCP for all five gases. The activation energy for permeation obtained at these different states exhibits different values. The value obtained in the liquid-crystalline state is the highest. Separation factors (P(O2)/P(N2)) and (P(CO2)/P(CH4)) exhibit an unusual behaviour when the temperature changes across T(g). They increase abruptly when the temperature increases and the phase changes from the glassy state to the liquid-crystalline state of the side-chain LCP. The fact that both permeability and selectivity increases with increasing temperature above the glass transition is attributed to the supermolecular arrangement of the liquid-crystalline state of the side-chain LCP.
IONIC-CONDUCTIVITY AND MORPHOLOGY OF POLYMER ELECTROLYTES BASED ON A SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANE CONTAINING OLIGOOXYETHYLENE SPACERS AND 6-CYANO-2-NAPHTHYL BENZYL ETHER MESOGENS
(1990-09-01)
HSIEH, CJ
;
HSIUE, GH
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
LIQUID-CRYSTALLINE POLYMERS CONTAINING MACROCYCLIC POLYETHERS .1. SIDE-CHAIN LIQUID-CRYSTALLINE COPOLYSILOXANES CONTAINING BENZO-[15]CROWN-5 BASED MESOGENIC SIDE GROUPS
(1990-04-01)
WEN, JS
;
HSIUE, GH
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
LIQUID-CRYSTALLINE POLYMERS CONTAINING MACROCYCLIC POLYETHERS .2. SIDE-CHAIN LIQUID-CRYSTALLINE COPOLYSILOXANES CONTAINING MESOGENIC UNITS BASED ON 1,3-DIOXANE-2,5-DIYL AND BENZO[15]-CROWN-5
(1991-10-01)
HSIUE, GH
;
WEN, JS
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
Synthesis and characterization of a series of copolysiloxanes containing crown ether and trans-1,3-dioxane based mesogens are presented. The phase behaviour of the copolymers was studied using differential scanning calorimetry and optical polarizing microscopy and compared with the phase behaviour of the corresponding copolysiloxane-containing crown ether and biphenyl-based mesogens. Two copolysiloxanes containing trans-2-(benzo-[15]crown-5)-5-(omega-alkan-1-yloxy)-1,3-dioxane side groups present no liquid-crystalline behaviour. The other four copolysiloxanes exhibit a nematic mesophase and undergo side-chain crystallization at low temperature. Two of the four copolysiloxanes which contain a trans-1,3-dioxane-2,5-diyl group in the mesogenic unit present lower isotropization temperatures and narrower mesophase ranges than the other two. This result reveals that replacing a phenyl ring in the mesogenic unit of a liquid-crystalline polymer by a trans-1,3-dioxane ring will decrease the thermal stability of the mesophase exhibited by this polymer.
ROOM-TEMPERATURE DIPHENYL-DIACETYLENE LIQUID-CRYSTALS
(1992-08-10)
WU, ST
;
MARGERUM, JD
;
MENG, HB
;
DALTON, LR
;
HSU, CS
Thirty new asymmetric diphenyl-diacetylene (PTTP) liquid-crystal homologs are synthesized and their physical properties characterized. In addition to the observed high birefringence and relatively low viscosity, several dialkyl PTTP homologs also possess a low melting point, wide nematic range, and low heat of fusion enthalpy. These properties are highly desirable for forming eutectic mixtures with entirely PTTP components. A binary eutectic showing a nematic range from 10 to 98-degrees-C is studied. These new liquid-crystal compounds and mixtures should be particularly useful for infrared applications.
SYNTHESIS AND CHARACTERIZATION OF BLOCK COPOLYMERS OF POLYETHER SULFONE WITH LIQUID-CRYSTALLINE POLYESTERS
(1993-04-01)
HSU, CS
;
CHEN, LB
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
A series of novel ABA block copolymers containing a liquid crystalline polyester (A) block and an amorphous polyether sulfone (B) block were prepared. The block copolymers were characterized by FT-IR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, optical polarizing microscopy and X-ray diffraction measurement. Calculated results obtained from FT-IR spectra and a hydrolysis study reveal that the block copolymers contain 17-33% weight of polyether sulfone segments. All the prepared block copolymers have shown a liquid crystalline property. The block copolymer containing 33% polyether sulfone presented a glass transition at 180-degrees-C and a crystalline to nematic phase transition at 278-degrees-C. The other copolymers have exhibited only a crystalline to nematic phase transition at approximately 255-degrees-C.
SYNTHESIS AND CHARACTERIZATION OF CHIRAL SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS CONTAINING LATERALLY SUBSTITUTED MESOGENIC SIDE GROUPS
(1990-04-22)
HSU, CS
;
CHU, PH
;
應用化學系
;
Department of Applied Chemistry
SYNTHESIS AND CHARACTERIZATION OF CHIRAL SMECTIC SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING 2,5-DISUBSTITUTED-1,3-DIOXANE BASED MESOGENIC SIDE-GROUPS
(1993)
JUANG, TM
;
LEU, YJ
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
The synthesis of three liquid crystalline polysiloxanes containing 4-[(S)-2-methyl-1-butoxycarbonyl]phenyl 4-(trans-5-alkanyl-1,3-dioxan-2-yl]benzoates side groups is presented. The phase behavior of both monomeric and polymeric liquid crystals was characterized by optical polarizing microscopy, differential scanning calorimetry and X-ray diffraction measurements. The monomer which contains eleven methylene units in the spacers is the only one to exhibit the enantiotropic smectic A and chiral smectic C phases. The polymer containing six methylene units in the spacers presents an enantiotropic smectic A phase while the polymer containing eleven methylene units in the spacers shows an enantiotropic smectic A and a monotropic smectic B phase.
SYNTHESIS AND CHARACTERIZATION OF FERROELECTRIC LIQUID-CRYSTALLINE POLYSILOXANES AND POLYMETHACRYLATES CONTAINING [(S)-2-METHYL-1-BUTOXY]PHENYL 4-(ALKYLOXY)BIPHENYL-4'-CARBOXYLATE SIDE GROUPS
(1992-12-21)
HSU, CS
;
LIN, JH
;
CHOU, LR
;
HSIUE, GH
;
應用化學系
The synthesis of side-chain liquid crystalline polysiloxanes and polymethacrylates containing 4- [(S)-2-methyl-1-butoxy]phenyl 4-hydroxybiphenyl-4'-carboxylate moieties as mesogenic units and aliphatic spacers containing respectively three to eleven methylene units is presented. Differential scanning calorimetry, optical polarizing microscopy, and X-ray diffraction measurements reveal chiral smectic mesomorphism for all polymers. Both polysiloxanes which contain respectively six and eleven methylene units in the spacers exhibit smectic A, chiral smectic C, and smectic B phases. Among the polymethacrylates prepared in this study, the polymethacrylate containing eleven methylene units in its spacers is the only one revealing smectic A and chiral smectic C phases. The results seem to demonstrate that the tendency toward chiral smectic C mesomorphism increases with increasing spacer length, and the thermal stability of the chiral smectic C mesophase is determined by the flexibility of the polymer backbone.
SYNTHESIS AND CHARACTERIZATION OF LIQUID-CRYSTALLINE COPOLYSILOXANES CONTAINING AZOBENZENE DYES AND 1,3-DIOXANE BASED MESOGENIC SIDE GROUPS
(1993-02-01)
HSIUE, GH
;
WEN, JS
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of nine side-chain liquid crystalline copolysiloxanes containing trans-5-(n-undecanyl)-2-(4-cyanophenyl)-1,3-dioxane and 4-(alkanyloxyphenylazo)benzonitrile side groups are presented. The azobenzene dye contents in the copolymers range from about 5 to 20 wt.-%. The nature of the mesophase exhibited by the copolysiloxanes depends very much on the dye concentration. Three copolysiloxanes which contain about 5 wt.-% azobenzene dye, display a smectic A phase while the other six copolysiloxanes which contain more then 10 wt.-% azobenzene dye, exhibit a nematic phase. All the obtained copolysiloxanes show a very low glass transition temperature and a very wide temperature range of mesophase.
SYNTHESIS AND CHARACTERIZATION OF LIQUID-CRYSTALLINE MONOMERS AND SIDE-CHAIN POLYMERS CONTAINING DIPHENYLDIACETYLENE MESOGENS
(1993)
LU, YH
;
HSU, CS
;
WU, ST
;
應用化學系
;
Department of Applied Chemistry
Nine unsymmetrically diphenyldiacetylenic monomers were prepared. The phase behavior as well as thermal polymerization of the obtained monomers were characterized by optical polarizing microscopy and DSC measurement. UV absorption, refractive indices and dielectric constants of the monomers were also measured. The olefinic monomers were subjected to undergo hydrosilylation reaction with poly(methylhydrogensiloxane) to form the polysiloxanes. Thermal behavior of the prepared polysiloxanes were studied.
SYNTHESIS AND CHARACTERIZATION OF NOVEL FLUORINATED DIPHENYLDIACETYLENIC LIQUID-CRYSTALS
(1993-10-01)
JUANG, TM
;
CHEN, YN
;
LUNG, SH
;
LU, YH
;
HSU, CS
Five series of asymmetric diphenyldiacetylenes containing a single fluorine, two fluorines or a trifluoromethyl group at one end and an alkyl, alkyloxy or alkenyloxy group on the other end, were prepared and characterized. Most of the 4-alkylphenyl-4'-fluorophenyldiacetylenes, 4-alkyloxyphenyl-4'-fluorophenyl-diacetylenes and 4-alkenyloxyphenyl-4'-fluorophenyldiacetylenes obtained exhibit an enantiotropic nematic phase and no smectic phase. However, most of the 4-alkyl-3', 4'-difluorodiphenyldiacetylenes, 4-alkenyloxy-3',4'-difluorodiphenyl-diacetylenes and 4-alkyl-4'-trifluoromethyldiphenyldiacetylenes show no meso-morphic behaviour. The effects of alkyl, alkyloxy, alkenyloxy, fluoro, 3,4-difluoro and trifluoromethyl end groups on the mesomorphic behaviour of the diphenyldiacetylenes prepared are discussed.
SYNTHESIS AND CHARACTERIZATION OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMETHACRYLATES CONTAINING FLUORINATED DIPHENYLDIACETYLENE SIDE-GROUPS
(1994)
LU, YH
;
TSAY, KT
;
HSU, CS
;
CHANG, HL
;
應用化學系
The synthesis of four side-chain liquid crystalline polymethacrylates containing either 4-alkanyloxy-4'-flourodiphenyldiactylenes or 4-alkanyloxy-3',4'-difluorodiphenyldiacetylenes side groups is presented. The phase behavior of both monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarizing microscopy. All synthesized polymethacrylates present nematic mesomorphism. The glass transition temperature of the obtained polymers decreases as the spacer length increases. The mesomorphic behavior of the prepared polymers depends very much on the degree of substitution of the mesogenic side groups on the polymer backbones.
SYNTHESIS AND CHARACTERIZATION OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING 4-ALKANYLOXYPHENYL TRANS-4-ALKYLCYCLOHEXANOATE SIDE GROUPS
(1991-06-01)
HSU, CS
;
LU, YH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
The synthesis and characterization of nine polysiloxanes containing 4-alkanyloxyphenyl trans-4-n-alkylcyclohexane side groups are described. Six monomers which contain a pentenyloxy or a hexenyloxy flexible spacer display a nematic mesophase, while the other three monomers which contain an undecenyloxy flexible spacer display nematic, smectic A and smectic E mesophases. All synthesized polymers present two smectic mesophases except one containing 4-hexanyloxyphenyl trans-4-n-butylcyclohexanoate side groups presents one smectic mesophase and one containing 4-undecanyloxyphenyl trans-4-n-pentylcyclohexanoate side groups presents three smectic mesophases. Trans-cis isomerization of mesogens and side chain crystallization did not occur for any of the synthesized polymers.
SYNTHESIS AND ELECTROOPTICAL PROPERTIES OF SOME FERROELECTRIC LIQUID-CRYSTALLINE POLYMERS
(1995-07-01)
HSU, CS
;
SHIH, LJ
;
HSIUE, GH
;
交大名義發表
;
應用化學系
The synthesis and characterization of several series of ferroelectric side chain polymers were presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurement were used to determine their thermal transitions and analyze their anisotropic textures. The influence of polymer backbones, flexible spacers, mesogenic cores as well as chiral end groups on the mesomorphic properties of the polymers was discussed. Furthermore, the dielectric relaxation properties of the obtained polymers were also evaluated.
SYNTHESIS AND MESOMORPHIC BEHAVIOR OF POLY(METHYLSILOXANE)S CONTAINING TRANS-CYCLOHEXANE-BASED MESOGENIC SIDE GROUPS
(1991-02-01)
HSU, CS
;
LU, YH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
The synthesis and characterization of poly(methylsiloxane)s containing either trans-4-methylcyclohexyl 4-alkenyloxybenzoate or trans-4-methylcyclohexyl 4'-alkenyloxybiphenyl-4-carboxylate mesogenic side groups are presented. All polymers except two which contain either trans-4-methylcyclohexyl 4-allyloxybenzoate or transmethylcyclohexyl 4-(5-hexene-1-yloxy)benzoate side groups, display liquid crystalline phases. The dependence of phase trasition temperature on the spacer length and the mesogenic core length as well as the thermal stalility of the prepared liquid crystalline polymers (LCPs) are described.
SYNTHESIS AND THERMAL-BEHAVIOR OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMETHACRYLATES CONTAINING TOLANE-BASED MESOGENIC SIDE-GROUPS
(1994-04-30)
HSIEH, CJ
;
WU, SH
;
HSIUE, GH
;
HSU, CS
;
應用化學系
The synthesis and characterization of nine polymethacrylates containing 4-alkoxy-4'-tri-fluoromethyltolane, 4-alkoxy-4'-cyanotolane, and 4-alkoxy-4'-nitrotolane side groups were described in this study. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry, optical polarizing microscopy, and x-ray diffraction. All of the obtained monomers exhibit no mesophase, while most of the synthesized polymers reveal enantiotropic mesomorphism. The polymethacrylate containing 4-propanyloxy-4'-nitrotolane side groups was the only one which shows no mesomorphic behavior. Both the spacer length and the nature of terminal groups have profound influence on the phase transition temperatures and thermal stability of the mesophase. The polymers with longer spacers tend to form a more ordered mesophase with a wider temperature range. Among three polymers with the same spacer length, the polymer with a trifluoromethyl terminal end group is inclined to form a more ordered mesophase than the other two polymers. No side chain crystallization occurred for all obtained polymers. (C) 1994 John Wiley & Sons, Inc.
SYNTHESIS AND X-RAY-DIFFRACTION OF FERROELECTRIC LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING 4'-(2-CHLORO-3-METHYL-PENTANOYLOXY)-4-ALKANYLOXYBIPHENYL SIDE-GROUPS
(1994-07-01)
HSIUE, GH
;
HSIEH, PJ
;
WU, SL
;
HSU, CS
;
應用化學系
The synthesis and characterization of side-chain liquid crystalline polysiloxanes containing (2S,3S)-4'-(2-chloro-3-methylpentanoyloxy)-4-alkanyloxybiphenyl side groups are presented. All the obtained polymers exhibit smectic mesomorphism. Those polymers containing a spacer length longer than 8 methylene units reveal respectively enantiotropic S(A), S(C)* and S(B) phases. The result demonstrates that the tendency toward the S(C)* phase increases with increasing the spacer length.