Polymer‐Polymer Interaction: Consistent Modeling in Terms of Chain Connectivity and Conformational Response

Abstract

AbstractSummary: An approach developed for the modeling of polymer solutions is extended to polymer blends. It accounts explicitly for the fact that the segments of a given macromolecule cannot spread out over the entire volume of the system (chain connectivity) and that the space a polymer molecule occupies may change after contact formation between the components of a mixture (conformational response ζ). The validity of the equation obtained for the Flory‐Huggins interaction parameter between polymers is tested by means of critical data published for the system PVME/PS. The measured phase diagrams can be modeled equally well by two limiting assumptions concerning the temperature dependence of the conformational response. However, using these two different sets of parameters to calculate the phase behavior for high molar masses of both polymers, leads to fundamental differences. One of them yields double critical points and predicts well defined critical compositions in the limit of infinite molar masses of both polymers, in contrast to the original Flory‐Huggins theory. The physical meaning of the different parameters is analyzed and the composition and temperature dependencies of the Flory‐Huggins interaction parameter resulting from the present modeling are compared with corresponding data reported in the literature.Double critical line (double critical concentration φDC as a function of m and n) calculated by means of Equation (12) and (13) using the system specific parameters given in row two of Table 2, and its projections into the different planes.imageDouble critical line (double critical concentration φDC as a function of m and n) calculated by means of Equation (12) and (13) using the system specific parameters given in row two of Table 2, and its projections into the different planes.