Describing the properties of chains of segments interacting via soft-core potentials of variable range with the SAFT-VR approach

We present a general development for the equation of state (EOS) of chain molecules composed of tangent spherical segments interacting with a soft repulsive potential and an attractive well. The method is based on a recent version of the statistical associating fluid theory for chain molecules with interaction potentials of variable range (SAFT-VR). In this communication we focus our attention on the properties of Lennard-Jones chains (LJC), using SAFT-VR and a sample recipe for the evaluation of the chain free energy that requires only a knowledge of the contact value of the cavity function of a Sutherland-6 system. We study the liquid-vapor coexistence properties for different values of the chain length. The results obtained are of similar accuracy to other EOS for LJC, but our approach is simpler and more general. We show that standard perturbation theories developed for simple liquids call also be used for chain molecules.