Macrophase Separation of Homopolymer Blends

Considering a binary blend composed of homopolymer A and B with volume fraction /a and /b = 1 - /a and assuming monomers of equal molecular size, the Flory-Huggins lattice model delivers an expression for the Gibbs free energy of 

By scaling the entropy term by a factor of N the model accounts for the fact that the monomers are covalently bonded in groups of N, preventing the independent dispersion on lattice sides. Therefore, blend phase behavior is controlled by the product xN, the segregation strength, capturing the two opposing enthalpic and entropic contributions [5]. 

In addition, the model delivers an expression for the dimensionless interaction parameter x, which describes the free-energy cost per monomer of contacts between 

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