Nematic-isotropic phase transitions of banana-shaped molecules with gauche- and trans-conformations

Abstract

A mean field theory is introduced to describe nematic phases of a banana-shaped molecule of a bend angle (θB ) with an axial chirality. We here take into account internal rotations: gauche- and trans-states, of the C-C bonds on the alkyl chains of the banana-shaped molecules. Using the Boltzmann statistics, the mean rotation angle is given as a function of temperature and the bond energy difference between the gauche- and the trans-states. We calculate phase diagrams on the temperature–bend angle plane and find six uniaxial and biaxial nematic phases with Landau points, depending on the bond energy.