Phase Transition and Molecular Polarizability Studies in Liquid Crystalline Mixtures

In this work, two mixtures with equal concentrations of 1) 4ꞌ-(6-(4-(pentylamino) methyl)-3-hydroxyphenoxy) hexyloxy) biphenyl-4-carbonitrile+-4-((4-(hexyloxy) benzylidene) amino) phenyl 4-butoxy benzoate and 2) 4ꞌ - (6-(4-(hexylamino) methyl)-3-hydroxyphenoxy) hexyloxy) biphenyl-4-carbonitrile+-4-((4-(octyloxy) benzylidene) amino) phenyl 4-butoxy benzoate, have been prepared. The transition temperature and optical texture are observed by using thermal microscopy. Density and birefringence studies are carried out on the above liquid crystalline mixtures. Using density and refractive indices data, the molecular polarizabilities are evaluated by using well-known Vuks and Neugebauer models. The molecular polarizability is also evaluated theoretically by Lippincott δ function model. The results reveal that the polarizability values are same in both experimental and theoretical methods.

Authors:

• M. Shahina
• K. Fakruddin
• C. M. Subhan
• S. Rangappa

Keywords:

• Liquid crystals
• optical textures
• transition temperature
• birefringence
• polarizability.

References:

[1] T. Chandrakumar, E.E. Burnell, Molecular Physics., 90, 3(1997).
[2] P.G. de Gennes and J. Prost, The Physics of Liquid Crystals, (Clarendon Press, Oxford), (1998).
[3] M.M. Naoum, G.R. Saad, R.I. Nessim, T.A.A. Aziz, Liquid Crystals.,25, 2 (1998).
[4] M.C. Chang, H.W. Chiu, X.Y. Wang, T. Kyu, N. Leroux, S. Champbell, L.C. Chien, Liquid Crystals., 25, 6 (1999).
[5] M.M. Naoum, R.I. Nessim, T.Y. Labeeb, Liquid Crystals.,27, 7 (2000).
[6] N.V.S. Rao, D.M. Potukuchi, VGKM Pisipati, Mol. Cryst. Liq. Cryst., 196, 71 (1991).
[7] A.P. Divya, K. Narayanamurthy, M.S. Madhava, D. Revannasiddaiah and R. Somashekar, Mol. Cryst. Liq. Cryst., 304, 9 (1997).
[8] S.R Kumaraswamy, D. Krishnegowda, R. Somashekar and D. Revannasiddaiah, Ind.J.Phys.,66A(5), 683 (1992).
[9] Obadovic D.Z, Stojanovic .M, Jovanovic-Santa .S, Cvetinov .M, Lazar .D, Vajda .A, Eber .N and Ristic .I, 2011 Molecular Cryst. Liq. Cryst. 547, 1736.
[10] Eren .S.S, Okutan .M, Koysal .O and Yerli .Y 2008 Chin. Phys. Lett. 25, 212.
[11] Sathyanarayana .P, Sadashiva .B.K and Dhara .D 2011 Soft Matter 7, 8556.
[12] Salamon .P, Eber .N, Buka .A, Gleeson .J.T, Sprunt .S and Jakli .A 2010 Phys, Rev. E 81, 031711.
[13] Cventinov .M, obadovic .D, Stajanovic .M, Lazar .D, vajda .A, Eber .N, Fodor-Csorba .K and Ristic .I 2013 liquid Crystals 40, 1512.
[14] Hong .S.H, Verduzco .R, Gleeson .J.T, Sprunt .S and Jakli .A 2011 Phys. Rev. E 83, 061702.
[15] Kundu .B, Roy .A, Pratibha .R and Madhusudana .N 2009 Appl. Phys. Lett. 95, 081902.
[16] Burmistrov, V.A., Zavyaloy, A.V., Novikoy, .I.V., Kuvshinova, S. A., and Aleksandriskii, V.V. (2005). Russ. J. Phys. Chem., 79, 130.
[17] Gogoi, B., Ghosh, T.K., and Alapati, P.R. (2005). Cryst. Res. Tech., 40, 709.
[18] Ajeetha, n., Ramakrishna NancharaRao, M., Datta Prasad, P.V., &Pisipati, V.G.K.M. (2005). Z. Naturforsch, 60(a), 746.
[19] George, N.A., Vallabhan, C.P.G., Nampoori, V.P.N., George, A.K., and Radhakrishnan, P. (2000). J. Phys., 33, 3228.
[20] Rajasree, K., Vidyalal, V., Radhakrishnan, P., Nampoori, V.P.N., Vallabhan, C.P.G., and George, A.K. (1998). Mater, Lett.,36, 76.
[21] Rananavare, S.B., Pisipati, V.G.K.M., and Freed, J.H. (1998). Liq. Cryst., 3, 957.
[22] Lippicott, E.R. &Dayhoff, M.O. (1960). Spectrochim. Acta, 16, 807.
[23] Lippicott, E.R. &Stutman, J.M. (1964). J. Phys. Chem., 68, 2926.
[24] J.W. Linnett, J. Am. Chem. Soc83, 2643 (1961).
[25] S. Chandrasekhar and N. V. Madhusudhana, J.Phy.(Paris) Colloq.C-4 Supp. 11-20, C4-24(1969).