Wholly aromatic thermotropic liquid crystalline polyesters of 3,3?-bis(phenyl)-4,4?-biphenol with 4,4?-benzophenone dicarboxylic acid

Abstract

A series of wholly aromatic, thermotropic polyesters, derived from 3,3′‐bis(phenyl)‐4,4′‐biphenol (DPBP), nonlinear 4,4′‐benzophenone dicarboxylic acid (4,4′‐BDA), and various linear comonomers, were prepared by the melt polycondensation reaction and characterized for their thermotropic properties by a variety of experimental techniques. The homopolymer of DPBP with 4,4′‐BDA had a fusion temperature (Tf) at 265°C, exhibited a nematic phase, and had a liquid crystalline range of 105°C. All of the copolyesters of DPBP with 4,4′‐BDA and either 30 mol % 4‐hydroxybenzoic acid (HBA), 6‐hydroxy‐2‐naphthoic acid (HNA), or 50 mol % terephthalic acid (TA), 2,6‐naphthalenedicarboxylic acid (2,6‐NDA) had low Tf values in the range of 220–285°C, exhibited a nematic phase, and had accessible isotropization transitions (Ti) in the range of 270–420°C, respectively. Their accessible Ti values would enable one to observe a biphase structure. Each of the copolymers with HBA or HNA had a much broader range of liquid crystalline phase. In contrast, each of the copolymers with TA or 2,6‐NDA had a relatively narrow range of liquid crystalline phase. Each of these polyesters had a glassy, nematic morphology that was confirmed with the DSC, PLM, WAXD, and SEM studies. As expected, they had higher glass transition temperatures (Tg) in the range of 161–217°C than those of other liquid crystalline polyesters, and excellent thermal stabilities (Td) in the range of 494–517°C, respectively. Despite their noncrystallinity, they were not soluble in common organic solvents with the exception that the homopolymer and its copolymer with TA had limited solubility in CHCl3. However, they were soluble in the usual mixture of p‐chlorophenol/1,1,2,2‐tetrachloroethane (60/40 by weight) with the exception of the copolymer with 2,6‐NDA. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 769–785, 1997

A novel thermotropic liquid crystalline copolyester containing phosphorus and aromatic ether moity toward high flame retardancy and low mesophase temperature

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Synthesis and characterization of certain photocrosslinkable thermotropic liquid crystalline random copolyesters containing arylidene moiety

“…The representative FTIR spectrum of polyester IVHC is shown in Figure 4: 3425 (overtone of C=O), 21 2975, 2938 (aliphatic), 1744 (ester carbonyl), 1696 (C=O of cyclopentanone ring), 1604 (C=C aromatic) 1287 to 1016 cm -1 (C–O–C of ester).…”

Prediction of liquid crystalline properties of poly(1,4-phenylene sebacate-oxybenzoate) by Monte Carlo simulation

“…During this study, it was found that the q of PPT is 753.5 Å which demonstrates its rigidity and LC behaviour. A previous simulation for PPT reports [62][63][64] the value of qZ751 Å which is in a good agreement with the result obtained using the parameters proposed for this study.…”

“…A critical value of q r of 5 suggests a nematic isotropic transition temperature [62][63][64] (T i ). During this study it was observed that at high temperature the molecules adopt, on average, a coiled conformation with a low persistence length but on reducing the temperature the width of the distribution about the straight conformation narrows and the persistence length increases.…”