Effect of alkyl chains length on properties of ferroelectric liquid crystals with the keto group attached to the molecule core

Bubnov, Alexej; Novotná, Vladimı́ra; Pociecha, Damian; Hamplová, Věra

doi:10.1080/01411594.2012.684880

Cited by 21 publications

(14 citation statements)

References 42 publications

(68 reference statements)

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“…This can be attributed to the unsymmetrical distribution of the electron density in the carbon–oxygen bonds in the ester molecule, which results in a higher dipole polarization than the mineral oil (Rudnick, ). A study by Bubnov et al () also suggested that the linking of the ester group to an alkyl chain can lead to substantial increases in the values of spontaneous polarization, which further results in higher relative permittivity values. Similar observations have been made by Gray (Shah and Tahir, ) for the relative permittivity of palm oil.…”

Section: Resultsmentioning

confidence: 99%

Effects of Molecular Structure on the Physical, Chemical, and Electrical Properties of Ester‐Based Transformer Insulating Liquids

Raof

Yunus

Rashid

et al. 2019

J Americ Oil Chem Soc

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This article presents the experimental studies carried out on the environmental friendly polyol ester insulating liquids to investigate the effect of molecular structure on the physical, chemical, and electrical properties. Six different polyol esters that can be produced from the transesterification of various methyl esters with neopentylglycol/trimethylolpropane alcohols were synthesized and compared with those of refined, bleached, and deodorized palm oil (RBDPO) and mineral transformer oil. The finding suggests that the physical properties like fire point, pour point, and viscosity are very much affected by the molecular weight and molecular composition of the polyol esters. The electrical properties are also highly influenced by the molecular structure-related characteristics, such as the polarity, dipole polarization, carbon chain length, and degree of branching. The results confirm the findings of previous studies that the polyol esters and RBDPO have more polarity and dipole polarization compared to mineral oil. The experimental evidence showed that the newly synthesized insulating liquids have favorable thermal and electrical properties, thus suggesting that the insulating liquids have the potential to replace conventional insulating liquids to provide a more sustainable power system in the future.

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Section: Resultsmentioning

confidence: 99%

Effects of Molecular Structure on the Physical, Chemical, and Electrical Properties of Ester‐Based Transformer Insulating Liquids

Raof

Yunus

Rashid

et al. 2019

J Americ Oil Chem Soc

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“…These types of compounds are synthesized in many research centres all over the world [9,10] and also in our group. [11] In recent time, mesogens containing such functional groups as keto moiety [12,13] and thioesters [14,15] have become more popular.…”

Section: Introductionmentioning

confidence: 99%

Mesomorphic andtrans–cis–transphotoisomerization studies of 4-[2-(4-hexyloxyphenyl)diazenyl]phenyl alkanoates

et al. 2014

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In this paper a full new homologues series of 4-[2-(4-hexyloxyphenyl)diazenyl]phenyl alkanoates is presented. All 15 synthesized compounds are mesogenic. Using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD) measurements four mesophases (nematic, smectic C, G and H) were identified. Moreover, with ultraviolet (UV) irradiation the photoisomerization was induced. Next the process of thermal relaxation in the dark was studied by using the UVÀvisible (UVÀVis) spectroscopy. The data gathered allowed us to calculate the kinetic constant of the photoisomerization. Additionally, the trans and cis isomers were separated by using column gel chromatography and their UVÀVis spectra were measured.

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“…Chiral self-assembling materials possessing smectic phases with ferroelectric properties on the nanoscale, specifically the lactic acid derivatives [ 9 – 15 ], attract considerable attention [ 16 – 19 ]. There are several considerable advantages of the lactic acid derivatives as a subclass of chiral self-assembling materials that makes them attractive [ 20 ], namely (i) the occurrence of a broad variety of basic LC phases, including the cholesteric, paraelectric, ferroelectric and antiferroelectric smectic phases as well as frustrated phases like the twist grain boundary – TGBA* and TGBC* phases or cubic SmQ* phase and re-entrant orthogonal and tilted phases; (ii) the utilisation of the lactic unit as a precursor of chiral centre minimises the synthetic cost with respect to the most commonly used chiral precursors; (iii) the melting points in the range of 5–70 °C are often desirable for application needs and the LC phases can easily be supercooled well below room temperature; and (iv) the lactic acid derivatives usually show no aging and are highly thermally as well as chemically stable. Due to the properties mentioned above, lactic acid derivatives demonstrate their high ability to be used as smart and functional dopants for the design and tailoring of the advanced multicomponent LC mixtures [ 21 – 25 ] and LC composite materials [ 25 – 32 ] and tuning their properties.…”

Section: Introductionmentioning

confidence: 99%

“…The replacement of the ether or ester groups (or their combination) by a keto group in order to link alkyl chains with the molecular core can result in a considerable increase in the values of the spontaneous polarisation [ 35 – 36 ]. Specifically, several series of the lactic acid derivatives [ 9 ] possessing a keto group utilised as a linkage between the non-chiral terminal alkyl chain, the molecular core [ 9 , 20 , 37 – 39 ] and the chiral part based on one [ 20 , 37 – 38 ], two [ 40 ] or three [ 9 , 39 ] lactate units have been intensively studied during last years.…”

Section: Introductionmentioning

confidence: 99%

Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

Bubnov

Vacek

Czerwiński

et al. 2018

Beilstein J. Nanotechnol.

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Several new lactic acid derivatives containing the keto linkage group far from the chiral part and short alkyl chains have been synthesized and characterised by polarising optical microscopy, differential scanning calorimetry, as well as electro-optic and dielectric spectroscopy. The materials possess a self-assembling behaviour on the nanoscale level as they form polar smectic liquid crystalline mesophases, namely the orthogonal paraelectric SmA* and the tilted ferroelectric SmC* phases, in a broad temperature range down to room temperature. A short helical pitch (≈120–320 nm), relatively high spontaneous polarisation (≈150 nC/cm2) and reasonable tilt angle values have been determined within the temperature range of the tilted ferroelectric SmC* phase. The obtained results make the new materials useful for the advanced mixture design and for further utilisation in electro-optic devices based on the deformed helix ferroelectric effect.

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Effect of alkyl chains length on properties of ferroelectric liquid crystals with the keto group attached to the molecule core

Cited by 21 publications

References 42 publications

Effects of Molecular Structure on the Physical, Chemical, and Electrical Properties of Ester‐Based Transformer Insulating Liquids

Effects of Molecular Structure on the Physical, Chemical, and Electrical Properties of Ester‐Based Transformer Insulating Liquids

Mesomorphic andtrans–cis–transphotoisomerization studies of 4-[2-(4-hexyloxyphenyl)diazenyl]phenyl alkanoates

Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

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