Browsing by Author "LU, YH"

Now showing 1 - 11 of 11

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 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 OF LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING DIPHENYLDIACETYLENE SIDE GROUPS
(1992-08-23)
HSU, CS
;
LU, YH
;
CHEN, YN
;
應用化學系
;
Department of Applied Chemistry
SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYMETHACRYLATES CONTAINING FLUORINATED DIARYLACETYLENE-BASED MESOGENIC SIDE-GROUPS
(1995)
WU, YH
;
LU, YH
;
HSU, CS
;
交大名義發表
;
應用化學系
The synthesis and characterization of side-chain liquid crystalline polymetnacrylates containing fluorinated diphenylacetylenic and naphthylphenylacetylenic side groups are presented. 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 methacrylate monomers exhibit no mesomorphic behavior. Polymers which contain eleven methylene units in their spacers reveal smectic mesomorphism. Polymers with a short spacer length, i.e., three or six methylene units, present either a nematic phase or no mesophase. The glass transition temperatures of the obtained polymers decrease as the spacer length increases. The polymers containing fluorinated naphthylphenylacetylenic side groups show a higher tendency to form a mesophase than those containing fluorinated diphenylacetylenic side groups. Incorporation of a lateral fluoro-substituent in the mesogenic core decreases not only the possibility to form a mesophase but also the thermal stability of the mesophase.
SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYOXETANES CONTAINING 4-(ALKANYLOXY)PHENYL TRANS-4-ALKYLCYCLOHEXANOATE SIDE-GROUPS
(1995-02-27)
LU, YH
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
The synthesis of side-chain liquid crystalline polyoxetanes containing 4-(alkanyloxy)phenyl trans-4-alkylcyclohexanoate side groups is presented. Differential scanning calorimetry, optical polarizing microscopy, and X-ray diffraction measurements reveal polymorphism of mesophases for all obtained polymers. Both spacer length and terminal alkyl length have a profound influence on the nature and thermal stability of the mesophases. Although the polyoxetane backbone is more flexible than the polymethacrylate backbone, side-chain crystallization did not occur for any of the synthesized polymers.
SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYOXETANES CONTAINING 4-DODECANYLOXYPHENYL TRANS-4-ALKYLCYCLOHEXANOATE SIDE-GROUPS
(1994-05-01)
LU, YH
;
CHANG, HL
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of side-chain liquid crystalline polyoxetanes containing 4-dodecanyloxyphenyl trans-4-alkylcyclohexanoate side groups are presented. All the obtained monomers exhibit smectic B mesomorphism, while all the obtained polymers present smectic A, smectic B and smectic G mesophases. A longer terminal alkyl group is leading to the formation of a more stable mesophase.
SYNTHESIS OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYSILOXANES CONTAINING TRANS-CYCLOHEXANE BASED MESOGENIC GROUPS
(1991-08-25)
HSU, CS
;
LU, YH
;
應用化學系
;
Department of Applied Chemistry
VAPOR-DEPOSITION POLYMERIZATION OF 2,5-DIMETHYLENE-2,5-DIHYDROFURAN
(1995-08-20)
LU, YH
;
HSU, CS
;
應用化學系
;
Department of Applied Chemistry