Molecular dynamics study of soft matter: Potential dependence of depletion forces

S Kim, JOURNAL OF THE KOREAN PHYSICAL SOCIETY, 61, 1102-1107 (2012).

DOI: 10.3938/jkps.61.1102

Depletion forces of colloids in a polymer solution in two dimensions are investigated by employing molecular dynamics simulations for different soft potential models between a colloid and a polymer and between two polymers. In order to see the local distributions of solvent particles, centro-symmetry parameters around the colloid and pair correlation functions between a colloid and a polymer are calculated. In order to see the direct effects of the solvent particles on the depletion forces, the volume fractions in the depletion zone are also calculated. Changes regarding depletion forces with gaps between two colloids can be understood with the introduction of these quantities. When the interaction between a colloid and a polymer is attractive, the gap between colloids acts as a shelter for the polymers, a layer occurs in the gap and the particles in the layer exert strong repulsive forces on the colloids. The layer of polymers formed in the depletion zone are found to play a dominant role in the behaviors of the depletion forces between the colloids.

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