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Updated: Jan 1, 2026

Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Effective interaction between colloids immersed in a polymer blend and their effect on the equation of state of this
1Institute of Theoretical Physics, University of Muenster, 48149 Muenster, Germany.
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.
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