Lattice model studies of the effect of chain flexibility on the nematic–isotropic transition. III. Completely flexible chain solutes in rigid rod solvents

Abstract

A steric, mean field, simple cubic lattice model using DiMarzio lattice statistics for mixtures of completely flexible chain solutes in rigid rod solvents is presented. The chain solutes depress the nematic–isotropic transition temperature of the pure solvent. The slopes of the two‐phase coexistence curves in the reduced temperature/mole fraction plane, solute and solvent order parameters, and solute activity coefficients for mixtures of rods and chains of various lengths are discussed and compared with relevant experimental data. The results indicate that although completly flexible chains in this model are too flexible compared with n‐alkane solutes, the chain flexibility of the solute is important in determining the ability of the solute to disrupt the nematic order of the solvent.