Statistical thermodynamics theory of phase equilibria in mixtures of thermotropic liquid crystals and flexible polymers

摘要

Lebwohl-Lasher model of nematogens and Flory-Huggins lattice model of polymers have been combined to describe the phase equilibria in mixtures of thermotropic small molecular liquid crystals and flexible polymers. The main aim is to calculate the phase diagram of the mixture in which the molecular weight of polymers is relatively high. It is found that the isotropic interaction between polymer segment and the liquid crystal is important and it results in the isotropic/isotropic demixing before isotropicematic demixing. The calculated results quantitatively agree with the experimental results quite well. Therefore, the results lend a support to the general validity of Lebwohl-Lasher model and Flory-Huggins model. Besides, the theory provides a theoretical method for designing the polymer dispersed liquid crystal electro-optical materials.