Effective interaction between colloids immersed in a polymer blend and their effect on the equation of state of this blend

Chervanyov A.I.

Zusammenfassung

Hypothesis Owing to the entropic interactions between polymers comprising a blend and surfaces of colloids immersed in this blend, the polymer inter-phases are formed between the colloids and blend. These inter-phases that are non-uniform both in density and composition, mediate the effective interaction between colloids immersed in a polymer blend. We surmise that there is an additional non-osmotic mechanism of the polymer mediated interactions specific to polymer blends, which is caused by the compositional non-uniformity of the above colloid-blend inter-phases. Theory By developing and making use of the random phase approximation based upon the Sanchez-Lacombe equation of state, we calculate the second virial coefficient of the effective interaction between colloids mediated by a polymer blend. The proposed approach takes into account finite compressibility of a polymer blend, as well as the specific (strong) interactions between dissimilar blend components. Using the obtained results, we derive the equation of state of a polymer blend filled with colloids. Findings We prove that the correlations imposed by the variations of the composition of a polymer blend cause a significant contribution to the polymer mediated interaction between colloids immersed in this blend. This contribution dominates over the osmotic contribution in the case of dense polymer blends.