Theoretical Study of Nematic to Isotropic Transition in Porous Media

• Authors: A. Govind , Kumarii Banerjee
• Languages of publication: EN

Abstracts

EN

Experimental observations show that the N-I transition temperature (T_{NI}) for liquid crystals embedded in solid porous materials is lower compared to that of the bulk liquid crystals and T_{NI} is reduced linearly with the inverse pore diameter. To explain this, various theoretical studies have been proposed. We propose to use the mean field approach. We modify the Maier-Saupe mean field theory to include the disordering effects of porosity as a disordering surface potential. A molecule near the surface is assumed to feel the mean field potential (the Maier-Saupe type) and also the surface induced potential. We calculate the values of the nematic order parameter and hence find the T_{NI} for different pore diameters. The weighted average of the order parameter is calculated considering the cylindrical symmetry of the pores. Our calculations on the variation of T_{NI} with pore diameter agree with experimental data. Also, the calculated values of specific heat peak decrease with decrease in pore radius, in agreement with experimental trends.

Keywords

EN

61.30.-v; 61.30.Cz; 64.70.M-; 61.30.Pq

Discipline

• 61.30.Pq: Microconfined liquid crystals: droplets, cylinders, randomly confined liquid crystals, polymer dispersed liquid crystals, and porous systems
• 61.30.Cz: Molecular and microscopic models and theories of liquid crystal structure
• 61.30.-v: Liquid crystals(for phase transitions in liquid crystals, see 64.70.M-; for liquid crystals as dielectric materials, see 77.84.Nh; for liquid crystals as optical materials, see 42.70.Df; for liquid crystal devices, see 42.79.Kr)
• 64.70.M-: Transitions in liquid crystals

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2016
• Volume: 130
• Issue: 3
• Pages: 748-750

Dates

published

2016-09

received

2015-12-21

(unknown)

2016-06-10

Contributors

author

A. Govind

• Department of Physics, Vijaya College, R.V Road, Basavanagudi, Bangalore, 560 004, India

author

Kumarii Banerjee

• Jain University, Bangalore, India

References

• [1] S. Chandrasekhar, Liquid Crystals, 2nd ed., Cambridge University Press, Cambridge 1992, doi: 10.1017/CBO9780511622496
• [1a] P.G. de Gennes, J. Prost, The Physics of Liquid Crystals, 2nd ed., Oxford University Press, London 1993
• [2] W. Maier, A. Saupe, Z. Naturforsch. 14a, 882 (1959)
• [3] D. Wilms, A. Winkler, P. Virnau, K. Binder, Phys. Rev. Lett. 105, 045701 (2010), doi: 10.1103/PhysLett.105.045701
• [4] G.P. Crawford, D.W. Allender, J.W. Doane, Phys. Rev. A 45, 8693 (1992), doi: 10.1103/PhysRevA.45.8693
• [5] G. Sinha, J. Leys, C. Glorieux, J. Thoen, Phys. Rev. E 72, 051710 (2005), doi: 10.1103/PhysRevE.72.051710
• [6] A. Schönhals, S. Frunza, L. Frunza, T. Unruh, B. Frick, R. Zorn, Eur. Phys. J. Special Top. 189, 251 (2010), doi: 10.1140/epjst/e2010-01329-5
• [7] S. Diez-Berart, D.O. Lopez, M.R. de la Fuente, J. Salud, M.A. Perez-Jubindo, D. Finotello, Liq. Cryst. 37, 893 (2010), doi: 10.1080/02678291003798156
• [8] G.S. Iannacchione, D. Finotello, Phys. Rev. Lett. 69, 2094 (1992), doi: 10.1103/PhysRevLett.69.2094
• [9] A. Zidansek, G. Lahajnar, S. Kralj, Appl. Magn. Reson. 27, 311 (2004), doi: 10.1007/BF03166325
• [10] R. Guegan, D. Morineau, R. Lefort, W. Beziel, M. Guendouz, L. Noirez, A. Henschel, P. Huber, Eur. Phys. J. E 26, 261 (2008), doi: 10.1140/epje/12007-10323-0
• [11] H. Masuda, K. Yada, A. Osaka, Jpn. J. Appl. Phys. 37, L1340 (1998), doi: 10.1143/JJAP.37.L1340
• [12] K. Nielsch, J. Choi, K. Schwirn, R.B. Wehrspohn, U. Gosele, Nano Lett. 2, 677 (2002), doi: 10.1021/nl025537k
• [13] H. Duran, M. Steinhart, H.J. Butt, G. Floudas, Nano Lett. 11, 1671 (2011), doi: 10.1021/nl200153c
• [14] A.V. Kityk, M. Wolff, K. Knorr, D. Morineau, R. Lefort, P. Huber, Phys. Rev. Lett. 101, 187801 (2008), doi: 10.1103/PhysRevLett.101.187801
• [15] C. Grigoriadis, H. Duran, M. Steinhart, M. Kappl, H.-J. Butt, G. Floudas, ACS Nano 5, 9208 (2011), doi: 10.1021/nn203448c
• [16] K. Uzelac, A. Hasmy, R. Jullien, Phys. Rev. Lett. 74, 422 (1995), doi: 10.1103/PhysRevLett74.422
• [17] A. Martian, M. Lieplak, T.Bellini, J.R. Banavar, Phys. Rev. Lett. 72, 4113 (1994), doi: 10.1103/PhysRevLett.72.4113
• [18] J. Ilnytskyi, S. Sokołowski, O. Pizio, Phys. Rev. E 59, 4161 (1999), doi: 10.1103/PhysRevE.59.4161
• [19] Monte Carlo - L. Wu, B. Zhou, C.W. Garland, T. Bellini, D.W. Schaefer, Phys. Rev. Lett. 51, 2157 (1995), doi: 10.1103/PhysRevE.51.2157
• [20] J. Xiaobao, W. Zi, Liq. Cryst. 40, 1116 (2013), doi: 10.1080/02678292.2013.795624
• [21] P. Aswini, A.S. Govind, Acta Phys. Pol. A 121, 625 (2012), doi: 10.12693/APhysPolA.121.625
• [22] A.S. Govind, P. Aswini, Liquid Cryst. 39, 1476 (2012), doi: 10.1080/02678292.2012.721903
• [23] P. Aswini, A.S. Govind, Liquid Cryst. 39, 701 (2012), doi: 10.1080/02678292.2012.672662
• [24] S. Dhara, N.V. Madhusudhana, Europhys. J. E 13, 401 (2004), doi: 10.1140/epje/i2003-10084-8
• [25] Z. Kutnjak, S. Kralj, G. Lahajnar, S. Zumer, Phys. Rev. E 68, 021705 (2003), doi: 10.1103/PhysRevE.68.021705

Identifiers

DOI

10.12693/APhysPolA.130.748