Classical density functional approach to depletion interaction of Lennard-Jones binary mixtures

In this article, we apply classical density functional theory to investigate the characteristics of depletion interaction in Lennard-Jones (LJ) binary fluid mixtures. First of all, in order to confirm the validity of our adopted density functional formalism, we calculate the radial distribution functions with theoretical approach and compare them with results obtained by molecular dynamics simu- lation. Then this approach is applied to the case of two colloids immersed in LJ solvent systems. We investigate the variation of depletion interaction with respect to the distance of two colloids in LJ binary systems. We find that depletion interaction may be attractive or repulsive, mostly depending on the bulk density of solvent and the temperature of binary system. For high bulk densities, the repulsive barrier of depletion force is remarkable when the total excluded volume of colloids touches each other and reaches a maximum. The height of repulsive barrier is related to the parameters of LJ potential and bulk density. Moreover, depletion force may exhibit attractive wells if the bulk density of solvent is low. The attractive well tends to appear when the surface-surface distance of colloids is half of the size of polymer and deepen with temperature lowering in a fixed bulk density. In contrast with the hard-spheres system, no oscillation of depletion potential around zero is observed.

Tuning the photonic properties of graphene oxide suspensions with nanostructured additives

Colloidal additives such as clay nanoplates and cellulose nanocrystals induce the ordering formation of graphene oxide via depletion interaction for hybrid photonic suspensions with temperature-sensitive properties.

Self-Assembly of Microscopic Rods Due to Depletion Interaction

In this article, using numerical simulations we investigate the self-assembly of rod-like particles in suspension due to depletion forces which naturally emerge due to the presence of smaller spherical depletant particles. We characterize the type of clusters that are formed and the evolution of aggregation departing from a random initial configuration. We show that eventually the system reaches a thermodynamic equilibrium state in which the aggregates break and reform dynamically. We investigate the equilibrium state of aggregation, which exhibits a strong dependence on depletant concentration. In addition, we provide a simple thermodynamic model inspired on the theory of self-assembly of amphiphilic molecules which allows us to understand qualitatively the equilibrium aggregate size distributions that we obtain in simulation.

Depletion-driven morphological transitions in hexagonal crystallites of virus rods

We show that the morphology of self-assembled superstructures of rod-like particles can be controlled from 1D fibers to 2D crystalline monolayers by tuning the particle attraction thanks to depletion interaction.

Application of Depletion Attraction in Mineral Flotation: I. Theory

We investigate the role of depletion interactions in the particle–bubble interactions that determine the attachment capability of particles on the bubble surface in flotation. In this article, we propose a theoretical model that explains how this attractive interaction could enhance flotation efficiency. Two optimum conditions are determined for the concentration and molecular weight of the depletion agent. The optimum concentration can be determined through the extent of surface activity of the depletion agents. The magnitude of the depletion attraction increases as the concentration increases; however, an increase in the concentration simultaneously enhances its surface concentration. The bubble surface adsorption of the depletion agent results in polymer brushes on the bubble surface that produce a large repulsive interaction. In contrast, the optimal molecular weight of the depletion agents is given by the interaction between the depletion agent sizes, which is determined by its molecular weight and Debye length which is determined by the solution ionic strength. We demonstrate that exploiting this depletion interaction could significantly enhance the flotation efficiency and in principal could be used for any particle system.