Theory of inhomogeneous polymers: Lattice model for polymer–polymer interfaces

An inhomogeneous polymer system is analyzed on the basis of a lattice model, in the spirit of the Flory–Huggins approach. Although the theory is developed in some detail, so as to point the way to future applications, only equations for the problem of polymer–polymer interfaces are derived. In the limit of broad interfaces the results of Helfand and Tagami are recovered. For the more general cases numerical results are presented.