Tunable dielectric and conductivity properties of two 4-n alkoxy benzoic acid

Patari, Sangita; Nath, A.

doi:10.1016/j.opelre.2017.12.002

Cited by 5 publications

(1 citation statement)

References 23 publications

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“…Данные о диэлектрической проницаемости и ее зависимости от температуры и состава исследуемой системы необходимы при разработке компонентов для устройств, работа которых основана на электрооптических эффектах [6][7][8][9]. У 4-н-алкилоксибензойных кислот, являющихся одним из компонентов жидкокристаллических материалов, используемых в средствах отображения информации, нематическая мезофаза в большинстве случаев обладает положительной анизотропией диэлектрической проницаемости [10][11][12][13].…”

Section: Introductionunclassified

Dielectric properties of the system: 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4᾽-methylaniline

Syrbu

Fedorov

Лапыкина

et al. 2021

Fine Chem. Technol.

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Objectives. Our aim was to study the dielectric properties of the 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4’-methylaniline system and reveal how different concentrations of N-(4-n-butyloxybenzylidene)-4’-methylaniline additives affect the dielectric properties of 4-n-pentyloxybenzoic acid.Methods. System properties were investigated using polarization thermomicroscopy and dielcometry.Results. We found that dielectric anisotropy changes its sign from positive to negative at the transition temperature of the high-temperature nematic subphase to the low-temperature one. The anisotropy of the dielectric constant of N-4-n-butoxybenzylidene-4’-methylaniline has a positive value and increases as to the system approaches the crystalline phase. The crystal structure of the 4-n-pentyloxybenzoic acid contains dimers formed by two independent molecules due to a pair of hydrogen bonds. The crystal structure of N-(4-n-butoxybenzylidene)-4’-methylaniline contains associates formed by orientational interactions of two independent molecules. 4-n-Pentyloxybenzoic acid dimers (270 nm) and associates of N-4-n-butoxybenzylidene-4’- methylaniline (250 nm) proved to have approximately the identical length. Considering the close length values of the structural units of both compounds and the dielectric anisotropy sign, we assume that the N-4-n-butoxybenzylidene-4’-methylaniline associates are incorporated into the supramolecular structure of the 4-n-pentyloxybenzoic acid. The specific electrical conductivity of the compounds under study lies between 10−7 and 10−12 S∙cm−1. The relationship between the specific electrical conductivity anisotropy and the system composition in the nematic phase at the identical reduced temperature, obtained between 100 and 1000 Hz is symbatic. However, the electrical conductivity anisotropy values of the system obtained at 1000 Hz are lower compared to those obtained at 100 Hz. At N-(4-n-butoxybenzylidene)-4’-methylaniline concentrations between 30 and 60 mol %, the electrical conductivity anisotropy values are higher than those of the individual component.Conclusions. A change in the sign of the dielectric constant anisotropy of the 4-n-pentyloxybenzoic acid during nematic subphase transitions was established. We showed that the system has the highest dielectric constant anisotropy value when components have an equal number of moles. Highest electrical conductivity anisotropy values are observed when the concentration of the N-4-n-butoxybenzylidene-4᾽-methylaniline system lies between 30 and 60 mol %.

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Section: Introductionunclassified

Dielectric properties of the system: 4-n-pentyloxybenzoic acid– N-(4-n-butyloxybenzylidene)-4᾽-methylaniline

Syrbu

Fedorov

Лапыкина

et al. 2021

Fine Chem. Technol.

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Thermal analysis and FTIR study of 4-n-hexadecyloxybenzoic acid (16OB)

Rudzki

Chruściel

Zalewski

et al. 2023

J Therm Anal Calorim

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We have carried out phase polymorphism studies of 4-n-hexadecyloxybenzoic acid (16OB) in temperature range: from 10 to 150 °C with the use of Differrential Scanning Calorimeter, Thermal Microscopic Polarization and Transmitted Light Intensity. 16OB is a liquid crystal which has smectic C phase (SmC) and rich polymorphism in solid phase. Particularly interesting is one of the transitions in solid state possessing characteristic clear exothermic effect (during heating cycle) which is associated with the transition between the metastable and stable phases. Fourier transform infrared spectroscopy as a function of temperature was used to analyze changes in the nature of hydrogen bonds. The exact analysis of effects shows an existence of the metastable phases. The stable and metastable phases differ from each other in the structure made of hydrogen bonds.

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