Effect of the anionic azo dye sunset yellow in lyotropic mixtures with uniaxial and biaxial nematic phases
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Dosyalar
Tarih
2020
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The effects of the anionic azo dye Sunset Yellow on the stabilization of lyotropic uniaxial and biaxial nematic phases and on the uniaxial to biaxial phase transitions were studied. The dye was added in different concentrations to the host ternary mixture of cationic surfactant dodecyltrimethylammonium bromide, 1-dodecanol, and water. Furthermore, an investigation examined the role of the dye in the lyotropic host mixture in comparison to some inorganic salts containing anions of the Hofmeister series. The following inorganic salts were added to the same host mixture: NaBr, NaNO3, NaClO3, NaI, NaSCN, and NaClO4. All the samples were investigated by polarizing optical microscopy, laser conoscopy, and small-angle X-ray scattering. The results indicated that (a) the anionic dye Sunset Yellow has a chaotropic character between that of the I- and SCN- ions, being similar to the last one, (b) it gives a larger biaxial nematic phase temperature range in the partial phase diagram in comparison with the SCN- ion and other inorganic salts, and (c) it shifts the temperatures of both uniaxial to the biaxial nematic phase transitions. The small-angle X-ray scattering results also indicated that, at least in the investigated concentration range, the dye is mainly located on the micelles' surfaces, just like a conventional ion, and that on increasing concentration the dye molecules induces higher aggregation number of the micelles. (C) 2020 Elsevier B.V. All rights reserved.
Açıklama
Anahtar Kelimeler
Lyotropic Liquid Crystal, Nematic Phase, Biaxial Nematic Phase, Anionic Azo Dye Sunset Yellow, Hofmeister Series, Polarizing Optical Microscopy, Laser Conoscopy, Small-angle X-ray Scattering
Kaynak
Journal Of Molecular Liquids
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
318
