The effect of chemical constitution of mesogenic monomer unit on liquid crystalline properties of polymers

Константинов, И. И.; Sitnov, A.A.; Grebneva, V.S.; Amerik, Yu.B.

doi:10.1016/0014-3057(83)90168-4

Cited by 8 publications

(6 citation statements)

References 7 publications

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“…It must be stressed that the strong exothermal peak in the first DSC curve does NOT correspond to any irreversible chemical reaction: a previously heated sample, dissolved in dioxane and freeze-dried again, showed exactly the same behaviour as the original sample. A similar exothermal peak with a small endotherm at higher temperatures below the clearing temperature was observed by Konstantinov et al 4) in a SC-LC polymethacrylate with a phenyl alkoxybenzoate mesogenic group having a 1OC 12 H 25 tail. They ascribed it to an improvement of the mesophase structure at higher temperatures.…”

Section: Polymer 2 B: S A1 -S Ad Polymorphismsupporting

confidence: 62%

“…Therefore one should be very careful when drawing conclusions from these data. In a paper by Konstantinov et al 4) the tail length was varied systematically in a series of five side-chain LC polymethacrylates with phenyl alkoxybenzoate mesogenic groups directly connected to the backbone. The general tendency in their results was that the transition temperatures decreased with increasing tail length due to the plasticizing effect of the tails.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Jansen

Addink

Nijenhuis

et al. 1999

Macromol. Chem. Phys.

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SUMMARY:The mesomorphic properties and thermal stability of side-chain LC polycarbonates with alkoxyphenyl benzoate side groups having a short spacer and alkoxy tails ranging from 1 to 8 carbon atoms were studied by DSC, X-ray diffraction and polarized light optical microscopy. All polymers have a smectic A structure. Mesogens having short tails organize preferably in a monolayer structure, and mesogens having long tails in a double layer structure. A sharp increase in the clearing temperatures and enthalpies as a function of tail length was observed. No clear relation between the tail length and the glass transition temperature was found. Both the T g and the clearing temperature show a strong dependence on the molecular weight. Up to about M -w = 20 000 a rapid increase in phase transition temperatures with increasing molecular weight was observed, eventually levelling off to a constant maximum value. The LC polycarbonates were found to be thermally stable up to about 200 8C. At higher temperatures, random chain scission, resulting in a rapid decrease in molecular weight, and unzipping, resulting in the formation of a five-membered cyclic carbonate, are the main initial degradation mechanisms. The degraded polymers have lower transition temperatures than the original ones.

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Section: Polymer 2 B: S A1 -S Ad Polymorphismsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Jansen

Addink

Nijenhuis

et al. 1999

Macromol. Chem. Phys.

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“…A study of such polymers based on the phenyl benzoate mesogen with variable length alkoxy tails indicates that both the T g and the clearing temperature decrease with increase in tail length up to 12 carbons, though both remain very high (180 to 130 and 254 to 208 °C, respectively). 52 The mesophases in the all-covalent polymers are typically bilayer or partially interdigitated bilayer phases, 48,51 in contrast to the effective single-layer phases of the present complexes. It is notable that the insertion of one or two methylene groups between a polyacrylate backbone and a biphenyl side chain converts a smectic A polymer into an amorphous polymer.…”

Section: Resultsmentioning

confidence: 94%

“…The thermal and structural order in these complexes may be compared with analogous all-covalent spacer-free side-chain (SC) polymers, 47 a number of which were among the first thermotropic SCLC polymers to be discovered 48,49 before the spacer concept was introduced 52 The mesophases in the all-covalent polymers are typically bilayer or partially interdigitated bilayer phases, 48,51 in contrast to the effective single-layer phases of the present complexes. It is notable that the insertion of one or two methylene groups between a polyacrylate backbone and a biphenyl side chain converts a smectic A polymer into an amorphous polymer.…”

Section: Resultsmentioning

confidence: 96%

Spacer-Free Ionic Dye−Polyelectrolyte Complexes: Influence of Molecular Structure on Liquid Crystal Order and Photoinduced Motion

et al. 2009

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A series of spacer-free ionic azobenzene-containing stoichiometric complexes was prepared from monosulfonated azo dyes and cationic polyelectrolytes [methylated poly(4-vinylpyridine) (PVP) and poly(dimethylaminoethyl methacrylate) (PDM)]. Their thermal and structural characteristics and optical responses, particularly photoinduced birefringence (PIB) and surface relief grating (SRG) inscription, were investigated as a function of selected molecular parameters. All of the complexes have high apparent T g values, 180-210°C, and show liquid crystal (LC) order of the single-layer SmA type from ambient to very high temperature, usually to degradation. The range of LC order is greater in the complexes of chromophores with longer alkyl tails and shorter in the complex of the chromophore with an OH end group and the complex of methyl orange (MO) with PDM. PIB, SRG quality, and diffraction efficiency were all shown to depend in a similar way on molecular structural features: the more rigid the molecular structure, the higher the PIB, the better its thermal and temporal stability, and the greater the SRG amplitude. Thus, a flexible alkyl unit in the polyelectrolyte component or in the chromophore tail or spacer reduces the optical performance, with a clear dependence on alkoxy tail length (e.g., no SRG formation was observed for the complex with a hexoxy tail), whereas the most rigid complex, MO/PVP, provides the best performance, contrasting with many previous literature reports that suggest a beneficial role for flexible spacers. The present paper shows that flexible moieties increase relaxation of photoinduced orientation. The hydroxyl end group also provides much improved PIB and SRG performance, attributed to its rigid structure along with a (temperature-dependent) physical cross-linking effect of H-bonding interactions.

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“…Mit den Methoden der Rontgenstreuung und der Kalorimetrie wurden Polymersysteme auf der Basis von strukturisomeren monomeren Gliedern MB-4 und M-04 untersucht [7]. Die Mischung der Homopolymere Poly-MB-4…”

Section: Mischungen Mesogener Gruppenunclassified

Ein molekulares Strukturmodell flexibelkettiger Polymere mit mesogenen Seitengruppen

Константинов

1986

Acta Polymerica

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A. V. TopEiev", 117912 GSP-1, Bfoskva V-71/LdSSR Eiii hfodell der molekularen Struktur von thermotropen, flussigkristallinen Polymeren mit kammartigem Aufbau wird vorgeschlagen. Entsprechcnd diesem Modell ist das Makromolekul mit einer Fernordnung der Lage seiner mesogenen Gruppen das kleinste Strukturelernent der iiberrnolekularen Struktur, in dcm physikalische Prozesse unabhangig von den Naclibarelernenten des Systems ablaufen. Die physiko-chemischen Eigenschaften derartiger Polymere werden durch die Intrakettenwechselwirkungen der mesogeneii Gruppen bestimmt. Dagegen beeinflussen die intermolekularen Wechsclwirkungeii sowolil die Deformationsprozcsse als auch die Spaniiungsrelaxation. Das vorgcschlagene Modell griindet sich auf experimentellc Ergebnisse aus lintcrsuchungen der Struktur und Eigenschaften sowohl der isolierten Makromolekule als auch der Polymere im kondensicrten Zustand und beschreibt eine Rcihe von Besonderhciten des Verhaltens fliissigkristalliner Polymere. MoAeKynspnaa moaenb c m p o e w s z u 6~o y e n~b z x nonumepos c 6 0~0 e b 6 m~ m e 3 0 z e n u b~~u zpynnamu IIpe,I(JIOXeHa

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The effect of chemical constitution of mesogenic monomer unit on liquid crystalline properties of polymers

Cited by 8 publications

References 7 publications

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5. Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

Spacer-Free Ionic Dye−Polyelectrolyte Complexes: Influence of Molecular Structure on Liquid Crystal Order and Photoinduced Motion

Ein molekulares Strukturmodell flexibelkettiger Polymere mit mesogenen Seitengruppen

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