The liquid‐crystal polymorphism of chiral thermotropic polyesters based on 4,4′‐(terephthaloyldioxy)dibenzoic acid and dipropylene glycols

Gallot, Bernard; Galli, Giancarlo; Chiellini, Emo

doi:10.1002/marc.1987.030080901

Cited by 14 publications

(2 citation statements)

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“…One objective of the present investigation was to determine the effect of N -methyl substituents on the physical properties of the resulting polymers. N -Methylated polyamides are well-known to yield polymers having lower melting transitions and significantly less crystallinity than analogous polyamides with unsubstituted amide units. − Many studies have shown that if the introduction of methyl or ethyl substituents into the flexible spacer units of liquid crystalline (LC) polyesters results in molecular asymmetry or dissymmetry, the crystal-to-liquid-crystal transition, the mesophase-to-mesophase transition, and the mesophase-to-isotropization transition temperatures are all lowered. ,− The introduction of these types of lateral substituents can also affect the ability of a liquid crystalline polymer (LCP) to crystallize upon cooling from the molten state. In the present case the short N -methyl substituents used in this investigation are expected to yield polymers having reduced thermal transition temperatures but not necessarily reduced crystallinity, because substitution on both amide nitrogen atoms does not impart either asymmetry or dissymmetry to the repeating units.…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystalline Poly(ester amide)s Based on N,N‘-Dimethyldiamines and an Aromatic Ester Triad

et al. 1997

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A series of thermotropic liquid crystalline poly(ester amide)s was synthesized based on various N,N‘-dimethylalkylenediamines and terephthaloyl bis(4-oxybenzoyl chloride), TBOC. Several different synthetic procedures were investigated to synthesize liquid crystalline (LC) polymers having a broad range of molecular weights. The highest molecular weight polymers were obtained by the low-temperature solution condensation of N,N‘-bis(trimethylsilyl)diamines and TBOC. Analyses of the polymers by wide angle X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy showed that the as-prepared crystalline polymers melted to form a nematic, liquid crystalline phase, which showed no evidence of recrystallization upon cooling. The LC polyesteramides with a 6-methylene spacer unit exhibited a monotropic behavior in contrast to the polymers or copolymers with a 12-methylene spacer unit which are enantiotropic. Changes in polymer conformation which occurred on heating in the solid state and in the liquid crystalline state were evaluated by solid state l3C cross polarization magic angle spinning NMR spectroscopy which showed that the polymers had considerable mobility at temperatures well below the crystalline melting point. The polymers, when precipitated from solution, contained mixtures of syn and anti amide units, but after melting, the syn amide unit was exclusively obtained indicating that it is likely the most thermodynamically stable conformation.

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Section: Introductionmentioning

confidence: 99%

Liquid Crystalline Poly(ester amide)s Based on N,N‘-Dimethyldiamines and an Aromatic Ester Triad

et al. 1997

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“…On the contrary, polymer 4 exhibits between 20 and 105 °C an orthogonal lamellar crystalline structure with a layer thick- For polymer 1 no definite lamellar structure was detected, according to previous results. 43 Ordered Smectic Structures. The X-ray diffraction patterns of the ordered smectic structures detected in samples 1, 2, and 4 are characterized by the presence in their low-angle region of one or two sharp reflections with Bragg spacings in the 1:2 ratio and the presence in the wide-angle region of two sharp reflections related to the lateral organization of the polymer chains on a centered rectangular lattice (Figure 5).…”

Section: Resultsmentioning

confidence: 99%

Chiral liquid crystal polymers. 10. Thermotropic mesomorphism in chiral isomeric polyesters

Chiellini¹,

Galli²,

Carrozzino³

et al. 1990

Macromolecules

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Asymmetrically branched alkyl spacers in liquid‐crystalline poly(alkylene 4,4′‐terephthaloyldioxydibenzoate)s

et al. 1992

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Poly[oxy-( 1,4-dimethyltetrarnethylene)oxycarbonyl-1,4-phenyleneoxyterephthaloyloxy-1,4phenylenecarbonyl] (1) was synthesized for the first time, and its thermal behaviour was studied by differential scanning calorimetry, thermooptical microscopy, and X-ray diffraction. The crystal to liquid-crystal and the mesophase to isotropic transition temperatures are lower by ca. 100 "C than the values reported for the unsubstituted polymer. Moreover, the formation of a threedimensional order is hindered in the case of the polymer with lateral substituents and can only be achieved by long annealing times.

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The liquid‐crystal polymorphism of chiral thermotropic polyesters based on 4,4′‐(terephthaloyldioxy)dibenzoic acid and dipropylene glycols

Cited by 14 publications

References 31 publications

Liquid Crystalline Poly(ester amide)s Based on N,N‘-Dimethyldiamines and an Aromatic Ester Triad

Liquid Crystalline Poly(ester amide)s Based on N,N‘-Dimethyldiamines and an Aromatic Ester Triad

Chiral liquid crystal polymers. 10. Thermotropic mesomorphism in chiral isomeric polyesters

Asymmetrically branched alkyl spacers in liquid‐crystalline poly(alkylene 4,4′‐terephthaloyldioxydibenzoate)s

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