Phase diagrams of mesomorphic mixtures

Abstract
We have combined the Maier Saupe theory [1] of the nematic-isotropic transition and the Flory Huggins theory of mixtures to describe the phase diagrams of two nematogens A + B. The two components can have different order parameters SA, SB in the mixture. We can then predict the morphology of the phase diagrams in term of a relatively small number (4) of interaction parameters. The final numerical calculations are restricted to cases where the clearing points of the two components are nearly equal (cases of chemical similarity). For certain sets of parameters we find a rather remarkable phase diagram with two consolute points — one at high temperatures in the isotropic phase and a second one at lower temperatures in the nematic phase. We also discuss the effects of chain length on the phase diagrams : when one component is a nematogenic polymer [2] with mesogenic side groups; and when the two components are polymers