Liquid structure, thermodynamics, and mixing behavior of saturated hydrocarbon polymers. 2. Pair distribution functions and the regularity of mixing

The role of liquid structure in the mixing properties of saturated hydrocarbon polymers was investigated using the intermolecular pair distribution functions obtained by molecular dynamics simulations. A correlation was noted between specific geometric features of the pure component distribution functions and various observations on macroscopic mixing characteristics relative to the solubility parameter formalism-regularity, attractive irregularity, repulsive irregularity-found earlier from neutron scattering studies of their blends. Ten component pairs are represented in these comparisons, and without exception they support the correlation. To our knowledge, it is the first relationship that provides an unambiguous connection between the pure component properties of polymers and how they mix.