Browsing by Author "JUANG, TM"

Now showing 1 - 5 of 5

SELECTIVITY IN THE PHASE-TRANSFER CATALYTIC-HYDROGENATION OF NITROBENZENE BY TRANSITION-VIII METALS
(1988-04-01)
JUANG, TM
;
HWANG, JC
;
HO, HO
;
CHEN, CY
;
交大名義發表
STEREOCHEMICAL STUDIES .60. NEIGHBORING PHENYL GROUP PARTICIPATION .1. STEREOSPECIFIC TRANSFORMATION OF L-PHENYLALANINE TO OPTICALLY-ACTIVE TROPIC ACID
(1984)
JUANG, TM
;
YAMADA, S
;
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 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 OF SIDE-CHAIN LIQUID-CRYSTALLINE POLYACRYLATES, POLYMETHACRYLATES AND POLYSILOXANES CONTAINING 4-CYANO-BIPHENYL 4-ALKANYLOXYBENZYL ETHER SIDE GROUPS
(1992-06-01)
JUANG, TM
;
CHANG, CF
;
HSU, CS
;
交大名義發表
;
應用化學系
The synthesis and characterization of side-chain liquid crystalline polyacrylates, polymethacrylates and polysiloxanes containing 4-cyanobiphenyl 4-alkanyloxybenzyl ether side groups are presented. All polymers display respectively a smectic A mesophase. The influence of the polymer backbone flexibility on the phase transition temperatures of the synthesized side-chain liquid crystalline polymers is discussed. The results demonstrate that flexible backbones enhance the decoupling of the motions of the side chain and main chain. Therefore, among three kinds of polymer backbones which contain the same mesogenic side groups, the most flexible one, i.e., polysiloxane, reveals a highest isotropization temperature and a widest temperature range of mesophase.