Effect of an external magnetic field on the phase behavior of the thermotropic melt of V-shaped molecules

Abstract

The effect of an external magnetic field on the phase behavior of a melt of V-shaped biaxial molecules has been examined within the Landau–de Gennes theory. The coefficients of the Landau-de Gennes free energy expansion have been found from microscopical model of V-shaped molecule that is assumed to be composed of two rigid rods formed by a sequence of monomer units. The simple qualitative model is proposed to take into account the dependence of magnetic anisotropy of V–shaped molecule on its molecular architecture. The regions of stability of paranematic, prolate uniaxial nematic and biaxial nematic phases have been found for thermotropic melt of bent shaped molecules subjected to an external magnetic field. The region of stability of biaxial nematic phase substantially increases as compared with the case of zero magnetic field.