scholarly journals Thermotropic Liquid Crystalline Polymers with Various Alkoxy Side Groups: Thermal Properties and Molecular Dynamics

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 992 ◽  
Author(s):  
Gi Tae Park ◽  
Jin-Hae Chang ◽  
Ae Ran Lim
Keyword(s):  
Molecular Dynamics ◽  
Thermal Properties ◽  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Magic Angle Spinning ◽  
Degree Of Crystallinity ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Crystalline Polymers ◽  
Thermotropic Liquid Crystalline Polymers

Two series of thermotropic liquid-crystalline polymers (TLCPs) were synthesized by reacting various dialkoxy terephthalate units with hydroquinone (HQ) and 2,6-naphthalene diol (Naph). The dialkoxy terephthalate moieties used in this study include 2,5-diethoxyterephthalate, 2,5-dibutoxyterephthalate, and 2,5-dihexyloxy-terephthalate. All the TLCPs synthesized in this study formed nematic phases. The molecular motions according to the length of the dialkoxy side groups in the TLCPs were evaluated by 13C cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and molecular dynamics of the TLCPs are found to be affected by the length of the dialkoxy side group and the aromatic diol unit in the main chain. Further, the thermal behaviors, liquid crystalline mesophases, and degree of crystallinity of the two series of TLCPs, i.e., HQ- and Naph-TLCPs, are compared.

scholarly journals Dependence of the Physical Properties and Molecular Dynamics of Thermotropic Liquid Crystalline Copolyesters on p-Hydroxybenzoic Acid Content

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 198 ◽  
Author(s):  
Gi Tae Park ◽  
Won Jun Lee ◽  
Jin-Hae Chang ◽  
Ae Ran Lim
Keyword(s):  
Molecular Dynamics ◽  
Thermal Properties ◽  
Liquid Crystalline ◽  
Magic Angle Spinning ◽  
Degree Of Crystallinity ◽  
Molar Ratio ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Hydroxybenzoic Acid ◽  
Thermal Stabilities

Two series of thermotropic liquid crystal copolymers (TLCPs) with different monomer structures and compositions were synthesized. The copolymers in the first series consisted of 2,5-diethoxyterephthalic acid (ETA), hydroquinone (HQ), and p-hydroxybenzoic acid (HBA), whereas those in the second series contained ETA, 2,7-dihydroxynaphthalene (DHN), and HBA. In both series, the molar ratio of HBA to the other monomers varied from 0 to 5. The thermal properties, degree of crystallinity, and stability of the liquid crystalline mesophase of the copolymers obtained at each HBA ratio were evaluated and compared. Overall, at each HBA content, the DHN-containing copolymer had better thermal properties, but the HQ-containing copolymer exhibited a higher degree of crystallinity and a more stable liquid crystalline mesophase. Furthermore, similar thermal stabilities were observed in both series. The dependence of the molecular dynamics of the TLCPs on the monomer structure was explained using 13C magic-angle spinning/cross-polarization nuclear magnetic resonance spectroscopy. An in-depth investigation of the relaxation time of each carbon revealed that the molecular motions of the TLCPs were greatly influenced by the structures of the monomers present in the main chain. The molecular dynamics of the HQ and DHN monomers in the two series were evaluated and compared.

Gas sorption in thermotropic liquid-crystalline polymers

1990 ◽  
Vol 9 (11) ◽  
pp. 1280-1283 ◽  
Author(s):  
C. Carfagna ◽  
E. Amendola ◽  
G. Mensitieri ◽  
L. Nicolais
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Gas Sorption ◽  
Crystalline Polymers ◽  
Thermotropic Liquid Crystalline Polymers

Transient isothermal elongational flow of thermotropic liquid crystalline polymers

Polymer ◽  
1993 ◽  
Vol 34 (1) ◽  
pp. 204-206 ◽  
Author(s):  
D.E. Turek ◽  
G.P. Simon ◽  
F. Smejkal ◽  
M. Grosso ◽  
L. Incarnato ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Elongational Flow ◽  
Liquid Crystalline Polymers ◽  
Crystalline Polymers ◽  
Thermotropic Liquid Crystalline Polymers
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