An Optical Study on Orientational Order Parameter and Molecular Polarizability in Benzylidene Anilines

Abstract:

Refractive indices measurements are carried out in four alkoxy benzylidene anilines viz., N-(p-n-methoxy and ethoxy benzaldehyde)-p-n-dodecyl and tetra decyl anilines, 1O.12, 1O.14, 2O.12 and 2O.14. First three compounds exhibit monovariant nematic phase while the last compound exhibits nematic and SmA phases with variable thermal ranges. The molecular polarizabilities are calculated from the refractive indices and the density using the well known internal field models by Vuks and Neugebauer. The molecular polarizability anisotropy is estimated from the Lippincott δ-function model as well as molecular vibrational methods. The order parameter is estimated using a) from the Haller’s extrapolation from molecular polarizabilities, b) from the scaling factors obtained from the equations by Vuks and Neugbeaur and c) directly from the birefringence - a method developed by Kuczynski et al without considering any internal field model to the liquid crystal molecule. The results evaluated from these methods are compared from one another and the limitations of the methods used are discussed.

• Periodical: Solid State Phenomena (Volumes 181-182)
• Pages: 102-105
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.181-182.102
• Online since: November 2011
• Authors: M. Ramakrishna Nanachara Rao, P.V. Datta Prasad, V.G.K.M. Pisipati, D. Madhavi Latha
• Keywords: Birefringence, Molecular Polarizability, Orientational Order Parameter

References

[1] P. G. de Gennes: Phys. Liq. Cryst. (Oxford University Press, London 1974).

[2] M. J. Stephen and J. P. Stralev: Rev. Mod. Phys. Vol. 46 (1974), p.617.

[3] A. Saupe and W. Maier: Z. Naturforsch. Vol. 16a (1961), p.816.

[4] S. Padmaja, M.R.N. Rao, P.V.D. Prasad and V.G.K.M. Pisipati: Z. Naturforsch Vol. 60a (2005), p.296.

[5] I. Haller, H.A. Huggins and M.J. Freisner: Mol. Cryst. Liq. Cryst. Vol. 16 (1972), p.53.

[6] S. Chandrasekhar and N. V. Madhusudhana: J. Phys. (Paris) Colloq. C-4 Supp. Vol. 11 C4, (1969).

[7] A. Saupe and W. Maier: Z. Naturforsch. Vol. 16a (1961), p.816.

[8] H. S. Subrahmanyam and D. K. Murthi: Mol. Cryst. Liq. Cryst. Vol. 22 (1973), p.239.

[9] E. R. Lippincott and J. M. Stutman: J. Phys. Chem. Vol. 68 (1964), p.2926.

[10] B. P. Rao and V. R. Murthy: Ind. Chem. J. XIII Vol. 17 (1979).

[11] W. Gordy: J. Chem. Phys. Vol. 14 (1946), p.305.

[12] I. Haller, H.A. Huggins, H.R. Lilienthal and T.R. Mcguire: J. Phys. Chem. Vol. 77 (1973), p.950.

[13] R.G. Horn: J. Phys. Vol. 39 (1978), p.105.

[14] Neugebauer and H. E.J. Can: J. Phys. Vol. 32 (1950), p.1.

[15] B. J. Zywucki and W. Kuczynski: IEEE Transactions Vol. 8 (2001), p.512.