Thermodynamics of Polymer-Clay Nanocomposites Revisited: Compressible Self-Consistent Field Theory Modeling of Melt-Intercalated Organoclays

We formulaic a compressible version of lattice self-consistent field theory (SCFT) to describe thermodynamic behavior of organically modified clays in polymer melt. The melt consists of the homopolymer matrix and a fraction of end-functionalized active chains, each chain having a single sticker end-group with strong affinity to the clay surface. We calculate the phase map for this system as a function of the melt composition and the strength of the sticker adhesion to the clay. It is shown that within the compressible SCFT model intercalated morphologies are favored in it significantly broader parameter range than was expected based oil the incompressible SCFT analysis. We provide a qualitative analysis of this result and discuss implications for the physics of nanocomposites in general.