Effect of Dopant Structure on Birefringences and Symmetric Tensor Invariants of Lyotropic Nematic Phases

Yıl 2018, Cilt: 14 Sayı: 2, 229 - 235, 30.06.2018

Erol Akpınar

https://doi.org/10.18466/cbayarfbe.403800

Öz

In this study,
we investigated the effect of the dopant structure on the birefringences and
the symmetric tensor invariants of lyotropic discotic nematic (N_D),
calamitic nematic (N_C) and biaxial nematic (N_B) phases.
Lyotropic host mixture consisted of potassium laurate (KL)/decanol
(DeOH)/water. Some dopant molecules were added to this host mixture to obtain
quaternary mixtures and to investigate the nematic phase properties by
polarizing optical microscopy and laser conoscopy. It was found that the dopant
molecules with aromatic ring affect the birefringences and symmetric tensor
invariants more efficiently than those with straight alkyl chain. 

Anahtar Kelimeler

Lyotropic liquid crystals, nematic phases, birefringences, symmetric tensor invariants, laser conoscopy, polarizing optical microscopy

Kaynakça

• 1. Akpinar, E, Reis, D, Neto, A.M.F, Effect of alkyl chain length of alcohols on nematic uniaxial-to-biaxial phase transitions in a potassium laurate/alcohol/K2SO4/water lyotropic mixture, Liquid Crystals, 2012, 39 (7), 881–888.
• 2. Neto, A.M.F, Galerne, Y, Levelut, A.M, Liebert, L, Pseudo-lamellar ordering in uniaxial and biaxial lyotropic nematics: A synchrotron X-ray diffraction experiment, Journal de Physique Lettres, 1985, 46 (11), 409-506.
• 3. Galerne, Y, Neto, A.M.F, Liébert, L, Microscopical structure of the uniaxial and biaxial lyotropic nematics, Journal of Chemical Physics, 1987, 87 (3), 1851–1856.
• 4. Akpinar, E, Reis, D, Yildirim, M, Neto, A.M.F, New lyotropic mixtures with non-chiral N-acylamino acid surfactants presenting the biaxial nematic phase investigated by laser conoscopy, polarized optical microscopy and X-ray diffraction, Materials, 2014, 7 (6), 4132–4147.
• 5. Lavrentovich, O.D, Looking at the world through liquid crystal glasses, Contemporary Mathematics, 2012, 577, 25-45.
• 6. Lawson, K.D, Flautt, T.J, Magnetically oriented lyotropic liquid crystalline phases, Journal of American Chemical Society, 1967, 89, 5489– 5491.
• 7. Rosevear, F.B, The mesomorphic phases of surfactant compositions, Journal of the Society of Cosmetic Chemists, 1968, 19, 581–594.
• 8. Yu, L.J, Saupe, A, Observation of a biaxial nematic phase in potassium laurate-1-decanol-water mixtures, Physical Review Letters, 1980, 45, 1000–1003.
• 9. Akpinar, E, Reis, D, Neto, A.M.F, Effect of Hofmeister anions on the existence of the biaxial nematic phase in lyotropic mixtures of dodecyltrimethylammonium bromide/sodium salt/1-dodecanol/water, Liquid Crystals, 2015, 42 (7), 973–981.
• 10. Galerne, Y, Marcerou, J.P, Temperature behavior of the order-parameter invariants in the uniaxial and biaxial nematic phases of a lyotropic liquid crystal, Physical Review Letters, 1983, 51, 2109–2111.
• 11. Freiser, M.J, Ordered states of a nematic liquid. Physical Review Letters, 1970, 24, 1041–1043.
• 12. Alben, R, Phase transitions in a fluid of biaxial particles. Physical Review Letters, 1973, 30, 778–781.
• 13. Shih, C.S, Alben, R, Lattice model for biaxial liquid crystals, Journal of Chemical Physics, 1972, 57, 3055-3061.
• 14. de Gennes, P.G, Prost, J, The physics of liquid crystals, Clarendon Press: Oxford, UK, 1993. Chapter 1.
• 15. Neto, A.M.F, Salinas, S.R.A, The physics of lyotropic liquid crystals: phase transitions and structural properties, Oxford University Press: Oxford, UK, 2005, p 24.
• 16. Akpinar, E, Otluoglu, K, Turkmen, M, Canioz, C, Reis, D, Neto, A.M.F, Effect of the presence of strong and weak electrolytes on the existence of uniaxial and biaxial nematic phases in lyotropic mixtures, Liquid Crystals, 2016, 43 (11), 1693-1708.
• 17. Berejnov, V.V, Cabuil, V, Perzynski, R, Raikher, Y.L, Lysenko, S.N, Sdobnov, V.N, Lyotropic nematogenic system potassium laurate-1-decanol-water: method of synthesis and study of phase diagrams, Crystallography Reports, 2000, 45(3), 493–500.
• 18. Akpinar, E, Reis, D, Neto, A.M.F, Lyotropic mixture made of potassium laurate/1-undecanol/ K2SO4/water presenting high birefringences and large biaxial nematic phase domain: a laser conoscopy study, European Physical Journal E, 2012, 35, 50 (1-9).
• 19. Akpinar, E, Canioz, C, Turkmen, M, Reis, D, Neto, A.M.F, Effect of the surfactant alkyl chain length on the stabilisation of lyotropic nematic phases, Liquid Crystals, 2018, 45 (2), 219-229.