Eutectic behaviour of binary mixtures composed of two isomeric lactic acid derivatives

Bubnov, Alexej; Podoliak, Natalia; Hamplová, Věra; Tomášková, Petra; Havlı́ček, Jaroslav

doi:10.1080/00150193.2016.1136776

Cited by 23 publications

(4 citation statements)

References 50 publications

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“…Finally, it can be concluded that the dielectric parameters of the studied materials are considerably influenced by the specific variations of the molecular structure as it has been described. The conducted studies should contribute towards a better understanding of the structure-property correlations for these specific classes of soft organic self-assembling materials derived from the lactic acid which may be utilized for further design of new liquid crystalline mixtures [57][58][59][60][61] aimed for advanced optoelectronic [62,63] and photonic applications.…”

Section: Summary Of the Results And Conclusionmentioning

confidence: 99%

Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Das

Barman

Das³

et al. 2019

Crystals

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The tilted ferroelectric SmC* phase of three structurally different series having three aromatic rings in the core structure connected by ester groups with different end alkyl chain lengths, all of which are derived from lactic acid, have been observed by broadband dielectric spectroscopy. Introduction of structural variations within the liquid crystalline compounds has led to the formation of chiral nematic N*, or the paraelectric orthogonal SmA* phase at higher temperatures. The dielectric spectra strongly depend both on the temperature as well as the specific molecular structure of the self-assembling compounds possessing the ferroelectric polar order. The results reveal a strong Goldstone mode in the ferroelectric SmC* phase with ~kHz relaxation frequency. In the SmC* phase, the real and imaginary parts of the complex permittivity increase up to certain temperature near the SmC*-N*/SmA* transition and then decrease with increasing temperature, perhaps due to the disruption of the molecular domains at the onset of the SmA*/N* phase transition. The dielectric strength attains a maximum value in the SmC* phase and then decreases near the SmA*/N* phase transition. The dielectric strength is also influenced by the lengths of the alkyl chain and the nature of the connecting unit of the constituent molecules. The relaxation time and the relaxation frequency are found to vary with the molecular structure of the studied ferroelectric compounds.

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Section: Summary Of the Results And Conclusionmentioning

confidence: 99%

Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Das

Barman

Das³

et al. 2019

Crystals

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“…Specifically, their attractiveness consists of the following: (i) the occurrence of a broad variety of basic LC phases, including cholesteric, paraelectric, ferroelectric and antiferroelectric smectic phases as well as a number of frustrated phases, like the twist grain boundary -TGBA* and TGBC* phases [53], cubic SmQ* phase [54] and re-entrant orthogonal and tilted phases [42, 55-56]; (ii) the utilisation of the lactic unit as a precursor of chiral centre considerably minimises the synthetic costs with respect to the most commonly used chiral precursors (e.g., (S)-2-octanol or (S)-2-methylbutan-1-ol); (iii) the melting points in the range of 5-70 o C are often desirable for application purposes and the LC phases can easily be supercooled below the room temperature; (iv) the lactic acid derivatives usually show no aging and are highly thermally as well as chemically stable and, finally, (v) good miscibility with LC materials of different chemical structure makes the lactic acid derivatives truly smart materials with high application potential. Due to all above mentioned properties, and especially the last one (v), lactic acid derivatives demonstrate their high ability to be used as functional dopants for the design and tailoring of advanced multicomponent LC mixtures [9,[11][12][57][58] and various LC composite materials [31][32][33][34][37][38]. They are also effective for controllable tuning of properties.…”

Section: Introductionmentioning

confidence: 99%

Lateral Substitution as Effective Tool for Tuning Self-Organising Behaviour of Chiral Mesogens

Hamplová¹,

Mironov²,

Cigl³

et al. 2021

Liq. Cryst. and their Appl.

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Thermotropic liquid crystals belong to an exciting class of self-organising materials, which are broadly utilised now, and, definitely will find advanced applications in future. The combination of fluidity and ordering together with specific electro-optical properties assures their extraordinary practical usefulness. However, the molecular structure -mesomorphic property relationship is still far to be well-established and understood despite more than a hundred years of their existence and intensive study. The design, synthesis and investigation of new liquid crystalline materials with various molecular structure type (rod-like, bend-shaped, disc-like, etc.) and weight (low molar mass, macromolecular) still remain an actual and highlighted task. In this mini-review we discuss relatively broad sub-class of chiral calamitic liquid crystalline materials derived from the lactic acid and give some specific examples on effective tuning of their mesomorphic and electro-optical behaviour using various types of lateral substitution of molecular core. Fluorine, chlorine, bromine and iodine atoms, as well as bulky methyl and methoxy groups are used as lateral substituents on the phenyl ring far from the chiral lactate group. The materials discussed in this work can be potentially used as smart dopants for design of advanced multicomponent mixtures targeted for future applications in opto-electronics and photonics.

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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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Eutectic behaviour of binary mixtures composed of two isomeric lactic acid derivatives

Cited by 23 publications

References 50 publications

Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Dielectric Properties of Chiral Ferroelectric Liquid Crystalline Compounds with Three Aromatic Rings Connected by Ester Groups

Lateral Substitution as Effective Tool for Tuning Self-Organising Behaviour of Chiral Mesogens

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

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