Thermal analysis of binary liquid crystalline mixtures

Bubnov, Alexej; Hamplová, Věra; Vajda, A.; Stojanović, Maja; Obadović, Dušanka Ž.; Éber, Nándor; Fodor‐Csorba, Katalin

doi:10.1007/s10973-006-7913-7

Cited by 38 publications

(8 citation statements)

References 31 publications

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“…Mixing compounds of different molecular structures has proven to be a useful tool to achieve lower transition temperatures in binary systems. Although bent-core compounds exhibit limited miscibility among themselves, a way to eschew this problem is to mix them with calamitic compounds [18][19][20][21][22][23][24], which could lead to unusual self-assemblies [25,26].…”

Section: Introductionmentioning

confidence: 99%

Mesophase behaviour of binary mixtures of bent-core and calamitic compounds

et al. 2013

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The mesophase behaviour of binary mixtures of bent-core and calamitic liquid crystals is presented. The nematogenic 4,6-dichloro-1,3-phenylene bis[4'-(10-undecen-1-yloxy)-1,1'biphenyl-4-carboxylate] (I) was the banana-shaped component. As the calamitic compound ethyl 4'-(9-decen-1-yloxy)-1,1'-biphenyl-4-carboxylate (II), similar to one arm of the bentcore molecule, was used which exhibits smectic phases in a wide temperature range. A total of 6 mixtures with different compositions were prepared and studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction on non-oriented samples. In the mixtures a nematic phase is not concomitant with smectic A phase, and the temperature range of both phases highly depends on the concentration of the comprising compounds. Lowered melting temperatures have been observed for all mixtures with respect to that of the pure compounds. Unforeseen finding is the induction of a monotropic SmC phase in mixtures with lowest concentration of the bent-core compound. Semi-empirical quantum-chemical calculations have also been performed. Based on the calculated molecular conformation, as well as on collected X-ray diffraction data, a model for a possible selfassembly of the banana-shaped and calamitic compounds is proposed.

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Section: Introductionmentioning

confidence: 99%

Mesophase behaviour of binary mixtures of bent-core and calamitic compounds

et al. 2013

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“…Prathiba et al 12 presented binary systems with a bent-core and a calamitic mixing component in which three mesophases are induced: a biaxial SmA phase and the 'banana phases' B 1 and B 6 . Binary systems with a bent-core mesogen and a calamitic mesogen were also reported by Bubnov et al 13 and Geetha et al 14 In this context it is interesting to note that the addition of few weight% of an achiral bent-core compound can significantly influence the elastic properties of a nematic solvent 15 or can enhance the chirality of a cholesteric host. [16][17][18] Moreover, small amounts of bent-core dopands are able to induce structural modifications, e. g. the formation of a glassy nematic state in a nematic solvent, 19 the transition of ferroelectric smectic phases of calamitic compounds into corresponding antiferroelectric phases 20,21 or the formation of an unusual SmA* twist state.…”

Section: Introductionmentioning

confidence: 56%

Induction of ‘banana phases’ in binary systems composed of bent-core and calamitic mesogen

et al. 2010

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“…Chiral liquid crystals derived from the lactic acid are intensively investigated due to definite advantages [19,25,26] with respect to other types of chiral molecular structures: chemical stability -no aging, reasonably low price, and a comprehensive variety of conventional and frustrated nematic and smectic phases stable in a broad temperature range. LC compounds with chiral part based on lactate group are actively used as: (i) chiral dopants while designing binary [27][28][29] and multicomponent functional mixtures [30,31]; (ii) reactive mesogens for macromolecular compounds used as side-chains for polymers [32][33][34] and elastomers [35,36]; (iii) functional dopants for organic photovoltaic cells [37][38][39] and matrices [40][41][42] for design of nanocomposite systems; and (iv) source of chirality for photosensitive low molar mass [21,[43][44][45] and macromolecular [20,34,[46][47][48] materials.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film

et al. 2020

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The control and prediction of soft systems exhibiting self-organization behavior can be realized by different means but still remains a highlighted task. Novel advanced nanocomposite system has been designed by filling of a stretched porous polyethylene (PE) film with pore dimensions of hundreds of nanometers by chiral ferroelectric liquid crystalline (LC) compound possessing polar self-assembling behavior. Lactic acid derivative exhibiting the paraelectric orthogonal smectic A* and the ferroelectric tilted smectic C* phases over a broad temperature range is used as a self-assembling compound. The morphology of nanocomposite film has been checked by Atomic Force Microscopy (AFM). The designed nanocomposite has been studied by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), small and wide-angle X-ray scattering and broadband dielectric spectroscopy. The effect of a porous PE confinement on self-assembling, structural, and dielectric behavior of the chiral LC compound has been established and discussed. While the mesomorphic and structural properties of the nanocomposite are found not to be much influenced in comparison to that of a pure LC compound, the polar properties have been toughly suppressed by the specific confinement. Nevertheless, the electro-optic switching was clearly observed under applied electric field of low frequency (210 V, 19 Hz). The dielectric spectroscopy and X-ray results reveal that the helical structure of the ferroelectric liquid crystal inside the PE matrix is completely unwound, and the molecules are aligned along stretching direction. Obtained results demonstrate possibilities of using stretched porous polyolefins as promising matrices for the design of new nanocomposites.

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Thermal analysis of binary liquid crystalline mixtures

Cited by 38 publications

References 31 publications

Mesophase behaviour of binary mixtures of bent-core and calamitic compounds

Mesophase behaviour of binary mixtures of bent-core and calamitic compounds

Induction of ‘banana phases’ in binary systems composed of bent-core and calamitic mesogen

Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film

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