Polymer mediated interactions between spherical fillers immersed in polymer blend.*

We analytically study the polymer mediated (PM) interactions between spherical particles immersed in a polymer blend. By making use of standard methods of the liquid state theory we have found out a novel mechanism of the PM interactions caused by non-uniformities in the local composition of the polymer blend induced by the particles. The relative significance of the contributions to the PM interaction potential due to the finite compressibility of the polymer blend and its compositional non-uniformity is found to drastically depend on the polymer-to-particle size ratio. In the protein limit of relatively small particles, the mechanism due to the compositional non-uniformity, specific to polymer blends, is shown to play a dominant role in the PM interactions.