Study of phase behavior in a system of linear hydrogen-bonded carboxylic acid homologues |
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| Authors: | EI Efremova AA Shiryaev ZA Kydryashova LA Nosikova SA Syrbue VV Chernyshev |
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| Institution: | 1. Department of Chemistry and Technology of Rare and Dispersed Elements and Materials for Electronics, Lomonosov Moscow State University of Fine Chemical Technologies, Moscow, Russiakatife@mitht.ru;3. Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia;4. Department of Chemistry and Technology of Rare and Dispersed Elements and Materials for Electronics, Lomonosov Moscow State University of Fine Chemical Technologies, Moscow, Russia;5. Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia;6. Department of Inorganic Chemistry, Ivanovo State University, Ivanovo, Russia;7. Chemistry Department, Lomonosov Moscow State University, Moscow, Russia |
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| Abstract: | The system of hydrogen-bonded liquid crystals formed from binary mixtures p-n-heptyloxybenzoic (I) acid and p-n-undecloxybenzoic (II) acid has been investigated by polarizing optical microscopy, differential scanning calorimetry, X-ray diffraction, and scattering and dielectric measurements. The T–X phase diagram was obtained for this system. All mixtures show enantiotropic smectic and nematic phases. The crystalline phase represents a (α, β) solid solution. At the 2:1 ratio of I to II, an intermediate phase – co-crystal γ – is formed. The co-crystal γ possesses a much wider mesophase range than the corresponding initial components. In contrast to mixtures based on the solid solutions having a positive anisotropy, the co-crystal shows a negative dielectric anisotropy in the mesophase. |
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| Keywords: | alkoxybenzoic acids hydrogen-bonded liquid crystals phase diagram |
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