Next Article in Journal
Phosphonic Acid Coupling Agent Modification of HAP Nanoparticles: Interfacial Effects in PLLA/HAP Bone Scaffold
Previous Article in Journal
Surface and Structural Properties of Medical Acrylonitrile Butadiene Styrene Modified with Silver Nanoparticles
Open AccessArticle

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

1
Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi 39177, Korea
2
Analytical Laboratory of Advanced Ferroelectric Crystals, Jeonju University, Jeonju 55069, Korea
3
Department of Science Education, Jeonju University, Jeonju 55069, Korea
*
Authors to whom correspondence should be addressed.
Polymers 2020, 12(1), 198; https://doi.org/10.3390/polym12010198
Received: 29 November 2019 / Revised: 8 January 2020 / Accepted: 10 January 2020 / Published: 12 January 2020
(This article belongs to the Special Issue Liquid Crystalline Polymers and Their Nanocomposites)
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. View Full-Text
Keywords: thermotropic liquid crystalline copolymer; p-hydroxybenzoic acid; thermal property; 13C solid-state nuclear magnetic resonance spectroscopy; molecular dynamics thermotropic liquid crystalline copolymer; p-hydroxybenzoic acid; thermal property; 13C solid-state nuclear magnetic resonance spectroscopy; molecular dynamics
Show Figures

Graphical abstract

MDPI and ACS Style

Park, G.T.; Lee, W.J.; Chang, J.-H.; Lim, A.R. Dependence of the Physical Properties and Molecular Dynamics of Thermotropic Liquid Crystalline Copolyesters on p-Hydroxybenzoic Acid Content. Polymers 2020, 12, 198.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop