Transitions in linear thermotropic polyesteramides

Hussain, Akhtar; McIntyre, J. E.; Milburn, A. H.

doi:10.1016/0032-3861(83)90180-5

Cited by 36 publications

(8 citation statements)

References 5 publications

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“…The same may be the reason for the crystalline nature of polyacrylates 3 a -d. The influence of hydrogen bonding on crystallinity and phase transitions of polymers has been studied by a number of workers. [4,[29][30][31][32][33][34][35] There have been many reports on the induction of liquid crystallinity through hydrogen bonding. [33][34][35] We have shown in an earlier publication that hydrogen bonding contributes to the formation of mesophases in the case of polyesteramide containing di-amide linkes.…”

Section: Thermal Properties and Phase Behaviourmentioning

confidence: 99%

Thermotropic side chain polyacrylates with azobenzene mesogenic groups: Synthesis and thermal behaviour

Saminathan

Pillai

2000

Macromol. Chem. Phys.

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Four side chain liquid crystalline (LC) polyacrylates containing substituted (methyl/long alkyl) azobenzene mesogens attached directly to the polymer backbone were synthesised. The polyacrylates were synthesised by free radical polymerization of the respective monomers, 4‐[(4‐acryloyloxyphenyl)azo]benzoic acid, 4‐[(4‐acryloyloxy‐3‐methylphenyl)azo]benzoic acid, 4‐[(4‐acryloyloxy‐2‐methylphenyl)azo]benzoic acid and 4‐[(4‐acryloyloxy‐2‐pentadecylphenyl)azo]benzoic acid. The monomers were obtained by acryloylation of the azo derivative prepared by the diazo coupling reaction between p‐aminobenzoic acid and the respective phenolic derivatives with varying hydrocarbon substituents. All polymers were soluble in polar solvents. The inherent viscosities of the polymers in DMSO at 28°C were in the range of 0.55–0.62 dL/g. The monomers and their polymers were characterised by elemental analysis, IR, UV‐vis, 1H and 13C NMR spectroscopies and WAXD. The thermal and phase transition behaviour of the polymers were investigated using DSC and a hot stage polarized light microscope (PLM). The polyacrylates exhibited stir opalescence and low viscosity characteristic of nematic phase on melting. However, the polymer with the long alkyl side chain (C15H31) was polymorphic with a smectic phase besides a nematic phase. The methyl substituted polymers showed only nematic phases. The effect of regioisomers on transition temperatures was significant. The carboxylic acid groups of the azophenyl mesogen are found to exist as hydrogen bonded dimers as indicated by IR, NMR and finally confirmed by WAXD. It is proposed that the long alkyl substituent might be involved in the stabilisation of the mesophase through its alignment parallel to the long axis of the molecule and might probably be supporting the formation of a smectic phase by reducing the transition temperature enough to maintain the layered arrangement of hydrogen bonded dimers.

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Section: Thermal Properties and Phase Behaviourmentioning

confidence: 99%

Thermotropic side chain polyacrylates with azobenzene mesogenic groups: Synthesis and thermal behaviour

Saminathan

Pillai

2000

Macromol. Chem. Phys.

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“…Polymer l to 8 were examined by polarizimg microscope with a heating stage, too; it was found that these polymers do not exhibit the thermotropic liquid crystalline behaw ior. It is possibly due to the intermolecular hydrogen bonding induced by amide group on lhe polymer chain, which raise the melting temperature of liquid crystalline polymer [13][14][15][16]. Thus, these polymers ([ to 8) are decomposed before they show thermotropic liquid crystalline phase during melting process.…”

Section: Properties Of Polymermentioning

confidence: 96%

Studies on the synthesis and properties of poly(amide-azomethine)

Chang

1994

J Polym Res

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Homopolymer and copolymer of poly(amide-azomethine) were synthesized from the corresponding diamines and dialdehydes. The polymerization was proceeded in the mixed solvent of o-chlorophenolandm-cresol(l:l by volume) at0°C for 18h. The inherent viscosities of the new aromatic poly(amide-azomethine)s are in the range of 0.51 to 2.31 dl/g. These polymers were soluble in sulfuric and formic acid. The TGA results show that no weight loss up to 400 °C under nitrogen atmosphere, which suggests the relatively good thermal stabilities.

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“…[4,[29][30][31][32][33][34][35] There have been many reports on the induction of liquid crystallinity through hydrogen bonding. [33][34][35] We have shown in an earlier publication that hydrogen bonding contributes to the formation of mesophases in the case of polyesteramide containing di-amide linkes. [33] A comparison of the DSC traces of the four polymers indicate that the presence of substituents attached to the pendant side chains has a remarkable influence on the phase transitions (see Tab.…”

Section: Thermal Properties and Phase Behaviourmentioning

confidence: 99%