Properties and applications of liquid-crystalline main-chain polymers

Dobb, M. G.; McIntyre, J. E.

doi:10.1007/3-540-12994-4_2

Cited by 161 publications

(41 citation statements)

References 57 publications

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“…This periodicity of about 500 nm has been reported for banded textures observed in both the thermotropic copolyesters and the aramids [407,430,[439][440][441][442][443][444][445]. The lateral banded textures exhibited by some of the thermotropes and the pleated sheet textures exhibited by some of the ararnids are observed only in materials which have a poorer degree of molecular orientation.…”

Section: Banded Structuresmentioning

confidence: 76%

Polymer applications

Sawyer¹,

Grubb²

1996

Polymer Microscopy

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Section: Banded Structuresmentioning

confidence: 76%

Polymer applications

Sawyer¹,

Grubb²

1996

Polymer Microscopy

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“…A significant amount of studies has been devoted to this class considerably with the increased amount of substitution for TA. Recently, we reported that of polymers based on modifications (1) to (3), each of which generally forms a nematic LC phase in the homopolymer of 3-phenyl-4,4 -biphenol ( MPBP ) with 4,4 -BDA has a fusion temperathe melt. However, in the case of modifications (4), the three common monomers, which are resture, T f , at 240ЊC, at which it exhibits a nematic LC phase and a narrow range of LC phase orcinol (RE), m-hydroxybenzoic acid (m-HBA) and isophthalic acid (IA), have been used to con-( 60ЊC ) .…”

Section: Introductionmentioning

confidence: 99%

“…Generally, homopolyesters have high crystal-to-nematic transitions, T m , Wholly aromatic, thermotropic polyesters are an because of their high enthalpy change and low important class of liquid crystalline polymers entropy change at these transitions. Therefore, (LCPs) because of their ease of processing in the several structural modifications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] of this class of polymers are required to decrease their T m values to a convenient level in order to prevent the lateral packing; (2) the copolymerization of differMany studies have been performed on wholly aromatic, thermotropic polyesters based on ent mesogenic (LC forming) monomers to decrease the symmetry of the polyester primary common nonlinear monomers, 17 -25 but a few studies have been reported to this class of polystructure; (3) the incorporation of noncoplanar 2,2-bis(substituted)-4,4-bibenzoate, monosubmers based on the nonlinear 4,4 -benzophenone dicarboxylic acid ( 4,4 -BDA ) . 26 -28 Skovby et stituted-terephthalate and monosubstituted-1,4-phenylene units in a copolyester in order to reduce al.…”

Section: Introductionmentioning

confidence: 99%

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

Han

Bhowmik

Frisch

1997

J. Polym. Sci. A Polym. Chem.

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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

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“…Many aromatic LCPs made with all para-disubstituted monomers melt at too-high temperatures to be melt processed. 1 However, if the regular chain structure is disrupted by partial replacement with a kink structure, a parallel offset (crankshaft), ring substitution, and/or a flexible spacer, the melting temperature is reduced and it is possible to obtain melt-processable thermoplastic copolyesters. 2,3 Today most commercial main-chain LCPs are manufactured by acidolysis, the exchange reaction between acetoxyaryl groups and carboxylic acid groups with the elimination of acetic acid (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

LCP aromatic polyesters by esterolysis melt polymerization

Choi

Padías

Hall

2000

J. Polym. Sci. A Polym. Chem.

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Polyarylates have previously been synthesized from acetate esters via esterolysis (loss of methyl acetate). This polycondensation can be extended to p‐substituted aromatic monomers for liquid crystal polyesters (LCPs). For AB‐type polymers, methyl p‐acetoxybenzoate and methyl 6‐acetoxynaphthoate were copolymerized to an LCP with reasonable molecular weights. Benzoate esters, methyl 4‐benzoyloxybenzoate (MBB) and methyl 6‐benzoyloxy‐2‐naphthoate (MBN), are also investigated. Several tin and antimony oxide catalysts were effective. The rate of esterolysis polymerization of MBB and MBN is slower than that of the corresponding acidolysis melt polymerization, but fast enough to give relatively high‐molecular‐weight polymers and similar thermal stability as commercial LCP prepared by acidolysis. Using these alternative benzoyloxy groups significantly reduced the color problem, because ketene loss cannot occur. Esterolysis melt polymerizations leading to AB/AABB‐type LCPs were performed using either dimethyl 2,6‐naphthalene dicarboxylate (DMND) or dimethyl terephthalate (DMT) with methyl 4‐acetoxybenzoate and phenylhydroquinone diacetate with tin and antimony catalysts. DMT‐based monomer compositions show much faster polymerization than DMND‐based compositions using antimony oxide catalyst. All these LCPs show a Tg in the 140–170 °C range as a result of the inclusion of the naphthalene and/or phenyl hydroquinone units in the polymer chain. Compositions completely off‐balanced on either side still lead to relatively high‐molecular‐weight copolyesters because either excess monomer can be removed during polymerization. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3586–3595, 2000

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Properties and applications of liquid-crystalline main-chain polymers

Cited by 161 publications

References 57 publications

Polymer applications

Polymer applications

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

LCP aromatic polyesters by esterolysis melt polymerization

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