LATTICE FLUID SELF-CONSISTENT FIELD-THEORY OF SURFACES WITH ANCHORED CHAINS

Self-consistent field theory is combined with lattice fluid theory to produce a robust model of the structure and interactions of chains anchored to smooth surfaces. The inclusion of holes in the lattice provides a means to investigate the effects of bulk solvent density and temperature on the interfacial properties. In a good solvent at the incompressible limit, the interactions between the surfaces are repulsive but become attractive with the addition of free volume and compressibility, e.g. in alkane liquids. As density decreases, solvent is expelled from the higher density interfacial region to the lower density bulk phase. The solvent expulsion raises the entropy and increases the strength of the attractive interactions between the surfaces. This behavior is analogous to phase separation of bulk mixtures at the lower critical solution temperature. A novel result is that the forces between the surfaces become attractive at a much higher density than required for phase separation in bulk systems.