Global phase diagram for monomer/dimer mixtures

The basic features of the global phase diagram associated with the generalized Flory dimer (GFD) equation of state for mixtures of square-well monomers and dimers are calculated. We first extend the GFD theory to square-well monomer/chain mixtures. Theoretical predictions for the compressibility factor as a function of volume fraction are in good agreement with discontinuous molecular dynamics simulation results for monomer/dimer and monomers/8-mer mixtures. The GFD-predicted global phase diagram for square-well monomer/dimer mixtures is estimated using a brute force method. The locus of critical points in the P–T plane is calculated over a grid of points in the Λ–ζ plane, where ζ is a measure of the difference between the monomer and dimer well depths and Λ is a measure of the strength of the attraction between monomers and dimers. The major topographical features of our global phase diagram are similar to those predicted for other equations of state.