DSC, Miscibility and X-Ray Studies of the Thermotropic Liquid Crystalline Polyesters with Aromatic Moieties and Flexible Spacers in the Main Chain

Bosio, L.; Fayolle, Bruno; Friedrich, Claude; Lauprêtre, F.; Meurisse, P.; Noël, Claudine; Virlet, J.

doi:10.1007/978-1-4613-2661-8_22

Cited by 18 publications

(8 citation statements)

References 24 publications

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“…However, both T m and T i of polymer I‐2 were lower than those of polymer I‐1 , as expected, and this was presumably due to the presence of eight longer methylene units present in the former in comparison with the four methylene units in the latter. These results are in excellent agreement with the reported results of other semiflexible thermotropic LCPs 42–44. The isotropization entropy (Δ S i ) of polymer I‐2 (Table 2) was higher than that of polymer I‐1 , and this suggested that the former had increased flexibility in the isotropic phase with respect to its smectic phase in comparison with the latter.…”

Section: Resultssupporting

confidence: 90%

“…The high degree of supercooling of an endotherm was indicative of T m . As for polymer I‐1 , its intermediate endotherm underwent high degrees of supercooling of 18 and 14 °C in the first and second cooling cycles, respectively, and this was in marked contrast to those of semiflexible thermotropic LCPs 42–44. The highest temperature endotherm exhibited a degree of supercooling of 10 °C in each of the cooling cycles, which was the lowest degree of supercooling among all of the endothermic transitions.…”

Section: Resultsmentioning

confidence: 94%

“…The intermediate endotherm was presumably related to the transition of the high‐order smectic phase to the low‐order smectic phase. Surprisingly, this endothermic transition underwent the highest degree of supercooling (20 °C) in each of the cooling cycles; this was in marked contrast to those of thermotropic LCPs 42–44. Usually, T m of an LCP exhibits a high degree of supercooling in the cooling cycle, but the LC‐to‐LC phase transition ( T LC/LC′ ) or T i exhibits characteristically little or no supercooling.…”

Section: Resultsmentioning

confidence: 94%

“…Usually, T m of an LCP exhibits a high degree of supercooling in the cooling cycle, but the LC‐to‐LC phase transition ( T LC/LC′ ) or T i exhibits characteristically little or no supercooling. In fact, the degrees of supercooling of various transitions of an LCP in the DSC thermograms can be used for the identification of T m , T LC/LC′ , and T i 42–44…”

Section: Resultsmentioning

confidence: 99%

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Main‐chain, thermotropic, liquid‐crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with aliphatic dicarboxylic acids

Bhowmik

Wang

Han

2003

J. Polym. Sci. A Polym. Chem.

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A series of main-chain, thermotropic, liquid-crystalline (LC), hydrogen-bonded polymers or self-assembled structures based on 4,4Ј-bipyridyl as a hydrogen-bond acceptor and aliphatic dicarboxylic acids, such as adipic and sebacic acids, as hydrogen-bond donors were prepared by a slow evaporation technique from a pyridine solution and were characterized for their thermotropic, LC properties with a number of experimental techniques. The homopolymer of 4,4Ј-bipyridyl with adipic acid exhibited high-order and low-order smectic phases, and that with sebacic acid exhibited only a high-order smectic phase. Like the homopolymer with adipic acid, the two copolymers of 4,4Ј-bipyridyl with adipic and sebacic acids (75/25 and 25/75) also exhibited two types of smectic phases. In contrast, the copolymer of 4,4Ј-bipyridyl with adipic and sebacic acids (50/50), like the homopolymer with sebacic acid, exhibited only one high-order smectic phase. Each of them, including the copolymers, had a broad temperature range of LC phases (36 -51°C). The effect of copolymerization for these hydrogen-bonded polymers on the thermotropic properties was examined. Generally, copolymerization increased the temperature range of LC phases for these polymers, as expected, with a larger decrease in the crystal-to-LC transition than in the LC-to-isotropic transition. Additionally, it neither suppressed the formation of smectic phases nor promoted the formation of a nematic phase in these hydrogen-bonded polymers, as usually observed in many thermotropic LC polymers. The thermal transitions for all of them, measured by differential scanning calorimetry, were well below their decomposition temperatures, as measured by thermogravimetric analysis, which were in the temperature range of 193-210°C.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Main‐chain, thermotropic, liquid‐crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with aliphatic dicarboxylic acids

Bhowmik

Wang

Han

2003

J. Polym. Sci. A Polym. Chem.

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“…The occurrence of a smectic E phase has also been proposed' by means of optical observations of analogus textural behavior m terphenyl-containing polyesters. 2 …”

Section: Polarization Microscopymentioning

confidence: 99%

Semiflexible Thermotropic Liquid-Crystalline Polymers: The Characterization of a Polyester-Polyether

Galli

Chiellini

Torquati

et al. 1989

Polym J

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ABSTRACT:The liquid crystal behavior of the thermotropic polyester derived from (4,4'-terephthaloyldioxy)dibenzoic acid and tetraethylene glycol was studied by differential scanning calorimetry, polarizing microscopy, and X-ray diffraction. The polymer sample exhibits the phase sequence isotropic-nematic-smectic A-smectic E-crystal, with decreasing temperature. Attention was devoted to the optical textures of the mesophases, as compared to those of low molar mass mesogens, and unusual high strength singularities were detected in the schlieren texture of the nematic phase. KEY WORDSLiquid-Crystalline Polymers/ Thermotropic Polyesters/ Liquid-Crystalline Polymorphism/ Smectic Mesophases / Schlieren Textures/ glycol ethers of different lengths:The thermotropic liquid-crystalline behavior of main chain polymers comprising alternating mesogenic units and flexible spacers is well established and attracts ever increasing interest. The great majority of such polymers presents only one mesophase, typically nematic ( or cholesteric ), but smectic phases have also been observed, including ordered smectic B 1 , E 2 , G 3 or H 4 phases. A few examples are known of mesophase polymorphism5, this feature being in marked contrast with what is most commonly observed in low molecular weight mesogens.In a previous paper 6 some of us reported on the synthesis and characterization of the thermotropic properties of a class of polyesters derived from 4,4' -(terephthaloyldioxy)dibenzoic acid (HTH) and ethylene (or propylene) Polymer samples having n = 2, 3, or 4 displayed two different enantiotropic liquidcrystalline phases, the lower temperature mesophase being a provisionally unidentified smectic phase and the higher temperature mesophase being recognized as nematic. 6 In the same context, unusual textural behaviors were observed in such polymers, especially at the mesophase-mesophase transition. All these features have stimulated further investigation and accordingly the polyester sample of that class with n = 4, here designated as HTH/TEG, was freshly prepared from HTH diacid chloride and tetraethylene glycol (TEG) and t To whom correspondence should be addressed.

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Main Chain Liquid Crystalline Semiflexible Polymers

Chiellini¹,

Laus

Demus³

et al. 1998

Handbook of Liquid Crystals Set

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DSC, Miscibility and X-Ray Studies of the Thermotropic Liquid Crystalline Polyesters with Aromatic Moieties and Flexible Spacers in the Main Chain

Cited by 18 publications

References 24 publications

Main‐chain, thermotropic, liquid‐crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with aliphatic dicarboxylic acids

Main‐chain, thermotropic, liquid‐crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with aliphatic dicarboxylic acids

Semiflexible Thermotropic Liquid-Crystalline Polymers: The Characterization of a Polyester-Polyether

Main Chain Liquid Crystalline Semiflexible Polymers

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