Phase Equilibria in Mixtures Containing Polystyrene and Nematic Liquid Crystals

Abstract

The phase behavior of two nematic liquid crystals in a polymer host is studied using the technique of Thermal Optical Analysis. Results are compared to the predictions of a recent molecular model due to Ballauff and found to give very good agreement for monodisperse polymers of sufficiently high molecular weight. Experimental findings include a widening of the two phase regime with increasing polymer chain length, exclusion of the polymer coils from the nematic phase and a sharp sensitivity of the phase behavior to the polydispersity of the polymer sample. All of these findings are in accord with the model and lend support to the general validity of the Flory-Ronca treatment of the anisotropic energetics responsible for thermotropic behavior.

Key Words:

• liquid crystal
• phase behavior
• statistical mechanics