Integral equation theory for the surface segregation from blends of linear and star polymers

An integral equation theory is investigated for the surface segregation from a blend of star and linear polymers. The molecules of both components are modeled as freely jointed tangent hard sphere molecules, and differ only in their topology, i.e. how the beads are connected. The surface is a hard wall impenetrable to the centers of the beads. The wall polymer reference interaction site model theory is used to study the surface segregation from this blend. The linear polymers are always in excess in the immediate vicinity of the surface as is expected from packing arguments. In most cases, the star polymers segregate to the surface if one looks at the integrated excess of star polymers over the linear polymers. This entropic segregation of the star polymers increases in magnitude if the functionality or arm length is increased.