A Molecular Statistical Theory of Smectic A Liquid Crystalline Mixtures: Thermal Stability of Smectic A Phase in Binary Mixtures

Abstract

A molecular statistical theory of smectic A liquid crystalline mixtures is presented. Both the intermolecular repulsions and the attractions are consistently introduced in similar to the previous work on smectic A liquid crystals. 1) The repulsive interaction is approximated in terms of the hard-core potential and is taken into account within the second-virial approximation. The temperature dependence of the order parameters over the smectic-nematic (or isotropic) and nematic-isotropic phase transitions is numerically calculated for several binary mixtures. In addition the phase diagrams of them are constructed. The smectic-nematic (or isotropic) transition temperatures in binary mixtures tend to be increased in comparison with the predicted values in terms of the linear approximation, being consistent with some experimental findings. It is also found that the symmetry-breaking component of one-body pseudo-potential contributes to the thermal stability of smectic A phase in smectic A binary mixtures.