Temperature Dependence of Surface Tension of Liquid Crystals at the Phase Transition

Abstract

The surface tension is calculated as the excess of the free energy per unit area, due to the presence of a surface layer, using Landau–de Gennes expansions, in the hypothesis of a first order transition in the bulk and taking into account the dependence of the surface free energy from the surface tilt angle. The surface order parameter is calculated and surface-ordered phase above the phase transition temperature has been found. A variety of calculated surface tension versus temperature curves with a jump at the phase transition, with positive or negative slope, well describing the experimental data from literature, have been attained.

Temperature Induced Surface Transitions in Liquid Crystal Planar‐Tilted Hybrid Cells

“…The variation of the anchoring tilt angle received the name of temperature induced surface transitions. MOLDOVAN et al 1995;MOLDOVAN et al 1996). In the present paper, temperature induced surface transitions are studied in hybrid cells for which the anchoring is asymmetrical: one of the cell's surface is treated for planar anchoring, the other is treated for a tilted one.…”

Surface Order Parameter and Polar Anchoring Energy in Nematic Liquid Crystals

“…The thermodynamic properties of physical systems presenting an ordered phase like the liquid crystal, are usually analysed in terms of Landau-de Gennes' theory (PING SHENG, PRIESTLEY; BOCCARA; GINZBURG, LANDAU; KAGANOV, OMEL'YANCHUC; BARBERO et al 1991;BARBERO et al 1992;MOLDOVAN et al;PONIEVIERSKI, SAMBORSKI;NANADI et al). The theory in its initial form considers an infinite system, with position independent parameters (BOCCARA).…”