Based on the PC-SAFT equation of state (EOS) a group contribution method (GCM) for polymers is developed to describe thermodynamic properties of the pure polymers as well as binary (co-)polymer/solvent liquid-liquid phase equilibria (LLE). The polymer parameters are obtained from group contributions by applying simple arithmetic and geometric mixing rules. Polymer classes of poly(olefines), poly(acrylates) as well as poly(methacrylates) are considered leading to the parameter set for five specific groups-CH3, >CH2, >(CH)- and >C< as well as the -(C=O)-O-group. The modeling approach is applied to pure polymer density and binary LLE data. Modeling results using the GCM polymer parameters are found to be in good agreement with experimental literature data. (C) 2012 Elsevier B.V. All rights reserved.