Eur. Phys. J. B 12, 83-90 (1999)
https://doi.org/10.1007/s100510050981

Statics and kinetics at the nematic-isotropic interface in porous media

Faculty of Physics, University of Bucharest, P. O. Box MG-11, Bucharest 76900, Romania

Corresponding author: ^a nita@scut.fisica.unibuc.ro

Received: 12 November 1998
Revised: 15 March 1999
Published online: 15 November 1999

Abstract

We extend the random anisotropy nematic spin model to study nematic-isotropic transitions in porous media. A complete phase diagram is obtained. In the limit of relative low randomness the existence of a triple point is predicted. For relatively large randomness we have found a depression in temperature at the transition, together with a first order transition which ends at a tricritical point, beyond which the transition becomes continuous. We use this model to investigate the motion of the nematic-isotropic interface. We assume the system to be isothermal and initially quenched into the metastable régime of the isotropic phase. Using an appropriate form of the free energy density we obtain the domain wall solutions of the time-dependent Ginzburg-Landau equation. We find that including a random field leads to smaller velocity of the interface and to larger interface width.