Dependence of Phase Transition of a Bent-Core Liquid Crystal on the Heating Rate

2010 ◽  
Vol 663-665 ◽  
pp. 787-790 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Heating Rate ◽  
Broad Peak ◽  
Crystal Phase ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Crystal Compound

A bent-core liquid crystal compound N,N-bis (4-propoxybenzylidene)benzene- 1,3-diamine was synthesized. Phase transition properties of the synthesized compound with the deferent heating rate were characterized with differential scanning calorimetry and polarized optical microscopy. , respectively. Our results demonstrated that the bent-core compound exhibited the completely undivided multi-phases in heating-rate ranges from 1oC/min to 6oC/min while it showed a broad-peak crystal phase in higher heating-rate ranges of 7-10oC/min for the first heating.

Synthesis and Mesomorphic Properties of a Series of Cholesteric Liquid Crystals

2010 ◽  
Vol 663-665 ◽  
pp. 759-762 ◽  
Author(s):  
Qing Lan Ma ◽  
Yuan Ming Huang
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Phase Transition Temperatures ◽  
Second Category ◽  
Mesomorphic Properties

A series of cholesterol liquid crystal compounds was synthesized. Phase-transition temperatures and mesomorphic textures of these synthesized compounds were characterized with differential scanning calorimetry and polarized optical microscopy, respectively. In these molecules the terminal ester chains CnH2n-1COO-, where n was the number of carbon atoms in the terminal ester chains, were linked to the cholesterol core. All of the synthesized cholesterol compounds exhibited mesophases for the first heating. However, as temperature decreased from their clearing points, their micrographs can also be divided into two categories, the first category exhibits branch-like mesophase textures for n in the range of 1-10 while the second category exhibits branch-like crystal textures for n in the range of 11-18.

Influence of Cooling Rates on Phase Transitions of Bent-Core Liquid Crystal 1,3-Phenylene-bis[4-(hexylcarboyloxyl)benzylideneamine]

2010 ◽  
Vol 428-429 ◽  
pp. 247-250 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Transitions ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Cooling Rate ◽  
Scanning Calorimetry ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Polarized Optical Microscopy ◽  
Fast Cooling

The influence of cooling rate on the phase transitions of a three-benzene-ring containing bent-core liquid crystal 1,3-phenylene-bis[4-(hexylcarboyloxyl)benzylideneamine] has been investigated by means of differential scanning calorimetry and polarized optical microscopy. Our results show that the cooling rates in the second cooling run pose significant effects on the phase transitions of the bent-core liquid crystal despite the cooling rates in the first cooling run pose little effects on the phase transitions. In the second cooling run, the banana phases survived only when the cooling rates were in the range of 14~15oC/min whereas both slow cooling rates which were less than 13oC/min and fast cooling rates which were higher than 16oC/min made the banana phases disappeared.

Synthesis and Mesomorphic Properties of Three-Benzene-Ring Containing Bent-Core Liquid Crystal 1,3-Phenylene-bis[4-(nonylcarboyloxyl) benzylideneamine]

2010 ◽  
Vol 428-429 ◽  
pp. 79-82 ◽  
Author(s):  
Yuan Ming Huang ◽  
Qing Lan Ma ◽  
Bao Gai Zhai
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Benzene Ring ◽  
Cyclic Heating ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Heating And Cooling ◽  
Phase Transition Temperatures ◽  
Mesomorphic Properties

A bent-core compound with three benzene-ring cores 1,3-phenylene-bis [4-(nonylcarboyloxyl)benzyl ideneamine] was synthesized. Its mesomorphic properties were characterized with differential scanning calorimetry and polarized optical microscopy, respectively. This kind of bent-core compound exhibited mesophases in the temperature range of 155-185oC for the first cooling but cyclic heating and cooling could lower the phase transition temperatures for this bent-core liquid crystal. Our results demonstrated that bent-core molecules with three benzene-ring cores can also form mesophases as those five benzene-ring containing bent-core molecules do.

scholarly journals New cholesteryl containing bent core liquid crystals

2013 ◽  
Vol 78 (5) ◽  
pp. 669-680 ◽  
Author(s):  
Cosmin-Constantin Huzum ◽  
Irina Carlescu ◽  
Gabriela Lisa ◽  
Dan Scutaru
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Microscopy ◽  
Liquid Crystalline ◽  
Benzoic Acids ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Acyl Chlorides ◽  
Esterification Reactions

The paper presents the synthesis and mesomorphic behavior of two new series of bent core liquid crystalline compounds based on a 1,3-dihydroxybezene core and containing a cholesteryl 6-oxyhexanoate wing. The two series were obtained by the esterification of the cholesteryl 6-(3-hydroxyphenoxy)hexanoate core with some 4-((4-(n-alkyloxy)phenyl)azo)benzoic acids (n-alkyl = n-hexyl ? n-dodecyl) or 4-(4-(n-alkyloxy)benzoyloxy)benzoic acids (n-alkyl = n-hexyl ? n-decyl). The esterification reactions were performed via the corresponding acyl chlorides or with the DCC / DMAP system. All the synthesized compounds evidenced enantiotropic liquid crystalline properties, with smectic type textures, when investigated by means of differential scanning calorimetry and polarized optical microscopy. Isotropisation and isotropic to liquid crystal transitions were relatively low (between 89 ? 1460C). The compounds containing the azo-aromatic linking group presented the largest range of stability of the mesophases (between 42 and 870C). All the investigated compounds were thermally stable in the existence range of the mesophases.

Synthesis and Mesomorphic Properties of Three-Ring Containing Bent-Core Liquid Crystal 1,3-Phenylene-bis(4-butoxybenzylideneamine)

2010 ◽  
Vol 428-429 ◽  
pp. 167-170
Author(s):  
Yuan Ming Huang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Optical Microscopy ◽  
Cyclic Heating ◽  
Scanning Calorimetry ◽  
Polarized Optical Microscopy ◽  
Temperature Range ◽  
Heating And Cooling ◽  
Mesomorphic Properties

A three-ring containing bent-core compound 1,3-phenylene-bis(4-butoxybenzylidene amine) was synthesized and characterized with differential scanning calorimetry and polarized optical microscopy. It exhibited mesophases in the temperature range of 48-54oC for the first cyclic heating and cooling. Our results demonstrated that three-ring containing bent-core molecules can form mesophases.

Characterization of Main-Chain Liquid Crystal Elastomers by Using Differential Scanning Calorimetry (DSC) Method

2015 ◽  
Vol 1123 ◽  
pp. 69-72 ◽  
Author(s):  
Supardi ◽  
Y. Yusuf ◽  
Harsoyo
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Basic Principle ◽  
Main Chain ◽  
Scanning Calorimetry ◽  
Mechanical Effects ◽  
Liquid Crystal Elastomers ◽  
Dsc Method

We performed an experiment to characterize the four samples of main chain liquid crystal elastomers (MCLCEs) by using differential scanning calorimetry (DSC) method. Basic principle of this method is that difference in the amount of heat required to increase the temperature of the sample and reference is measured as a function of temperature. The temperature between the sample and reference is maintained nearly the same throughout the experiment. There were four samples with different concentrations of crosslinker we have taken, namely 8%, 12%, 14%, and 16%. The results showed that the phase transition from nematic to isotropic obtained by this method had correlation with their thermo-mechanical effects.

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