Preparation of Main-Chain Thermotropic Polyesters With Two Types of Mesogens Connected Alternatively by Aliphatic Spacers

Guo, Qing; Huang, Yan; Zhang, Yuying; Zhang, Baolong

doi:10.1080/00222341003772241

Cited by 3 publications

(1 citation statement)

References 33 publications

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“…Compared with thermosetting liquid crystal polymers, thermoplastic liquid crystal polymers are the more ideal objects for research because of their clear structures, repeatability in molding, and recyclability [39][40][41]. Most industrial thermoplastic liquid crystal polymers are all-aromatic liquid crystal polyesters, which possess advantages of high strength, high modulus, and outstanding melt fluidity.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Zhong

Ruan

2022

Research

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Enhancing thermal conductivity coefficient ( λ ) of liquid crystal polyesters would further widen their application in electronics and electricals. In this work, a kind of biphenyl-based dihydroxy monomer is synthesized using 4, 4’-biphenyl (BP) and triethylene glycol (TEG) as raw material, which further reacts with three different dicarboxylic acids (succinic acid, p-phenylenediacetic acid, and terephthalic acid, respectively) by melt polycondensation to prepare intrinsically highly thermally conductive poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) succinate (PEOS), poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) p-phenyldiacetate (PEOP) and poly 4’, 4”’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) terephthalate (PEOT), collectively called biphenyl-based liquid crystal polyesters (B-LCPE). The results show that B-LCPE possess the desired molecular structure, exhibit smectic phase in liquid crystal range and semicrystalline polymers at room temperature, and possess excellent intrinsic thermal conductivities, thermal stabilities, and mechanical properties. λ of PEOT is 0.51 W/(m·K), significantly exceeds that of polyethylene terephthalate (0.15 W/(m·K)) which has similar molecular structure with PEOT, and also higher than that of PEOS (0.32 W/(m·K)) and PEOP (0.38 W/(m·K)). The corresponding heat resistance index ( T HRI ), elasticity modulus, and hardness of PEOT are 174.6°C, 3.6 GPa, and 154.5 MPa, respectively, and also higher than those of PEOS (162.2°C, 1.8 GPa, and 83.4 MPa) and PEOP (171.8°C, 2.3 GPa, and 149.6 MPa).

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Section: Introductionmentioning

confidence: 99%

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Zhong

Ruan

2022

Research

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Thermotropic Liquid Crystalline Polymers

Jaffé

Cheng

Chung

et al. 2018

Encyclopedia of Polymer Science and Technology

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Herein we present recent studies on the nature of thermotropic liquid crystalline polymers (LCPs) and their progress. Side‐chain liquid crystals are also discussed briefly, showing the similarities and differences between these closely related molecules. We summarize and review the newly developed thin‐film polymerization technique for the investigation of liquid crystalline formation as a function of monomer moieties, and for the study of reaction kinetics, evolution of liquid crystal texture, and surface energy during polycondensation reactions. We also highlight various modification approaches to yield main‐chain LCPs suitable for conventional processing equipment, without compromising the unique liquid crystalline characteristics and superior mechanical properties. The thermal stability, degradation behavior, and crystallization kinetics of commercially available main‐chain LCPs are recapitulated. Attention is also given to the rheology, polymer blends, micro‐ and nanostructures, processing of LCPs, and their applications. In the past decade, investigations of thermotropic LCPs have decreased from the high interest and publication rate of the latter part of the twentieth century. However, the number of monomer combinations giving rise to main‐chain thermotropic polymers has increased and the origin of LCP rheology and morphology have been elucidated. The most important new work is the invention and description of thermotropic thermosets.

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Aromatic liquid crystalline copolyesters with low T_m and high T_g: Synthesis, characterization, and properties

Wei

Cakmak

Chen

et al. 2014

J of Applied Polymer Sci

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In this study, a series of aromatic copolyesters P‐BPAx with lower melting temperature and higher glass transition temperature derived from hydroxybenzoic acid (HBA), 6‐hydroxy‐2‐naphthoic acid (HNA), bisphenol A (BPA) and terephthalic acid (TA) were synthesized via melt polymerization. The copolyesters were characterized by FTIR, solid state 13C NMR, DSC, TGA, polarized optical microscopy, X‐ray diffraction, and rheometry measurements. With addition of BPA, the resulting copolyester's melting temperature decreased from 260 to 221°C and its glass transition temperature increased from 70 to 135°C, compared with the parent copolyester P‐HBA70 (HBA/HNA copolymer). With exception of copolyester P‐BPA5.0 (225–280°C), the copolyesters could maintain liquid crystalline behavior in a broad temperature range from 230°C to higher than 410°C. The ability to form nematic liquid crystalline phase disappeared when BPA concentration became higher than 15 mol %. X‐ray diffraction analysis showed crystallinity decreased as the BPA content increased. A slightly distorted O" and a substantially distorted O′ orthorhombic phase was observed for P‐BPA2.5. Upon annealing at 220°C, the O" phase disappeared and the O′ phase became stronger gradually. Rheology study data showed the ability to process the copolyesters improved in those compositions containing <2.5 mol % BPA. Continuing to increase concentrations of BPA, they became intractable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40487.

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Preparation of Main-Chain Thermotropic Polyesters With Two Types of Mesogens Connected Alternatively by Aliphatic Spacers

Cited by 3 publications

References 33 publications

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Thermotropic Liquid Crystalline Polymers

Aromatic liquid crystalline copolyesters with low T_m and high T_g: Synthesis, characterization, and properties

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Preparation of Main-Chain Thermotropic Polyesters With Two Types of Mesogens Connected Alternatively by Aliphatic Spacers

Cited by 3 publications

References 33 publications

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers

Thermotropic Liquid Crystalline Polymers

Aromatic liquid crystalline copolyesters with low Tm and high Tg: Synthesis, characterization, and properties

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Aromatic liquid crystalline copolyesters with low T_m and high T_g: Synthesis, characterization, and properties