(189bu) Thermodynamic Modeling of Saturn Particles and Phase Behavior in Patchy Colloid Mixtures

Research on patchy colloids has attracted ongoing interest and the fabrication of patchy colloids with different number, size, shape, and relative location of attractive surface patches makes patchy colloids a good candidate as building blocks to form much more complex advanced materials. Particles with Saturn ring like bonding sites have been fabricated in experiment and they can be used to stabilize Pickering membranes¹ . In this work we extend a cluster size distribution theory^2,3 to study the thermodynamics and phase behavior of binary patchy colloid mixtures. The binary mixtures contain solute colloids with a single Saturn ring like bonding site (Saturn solute) which can form multiple bonds with solvent particles. The solvent particles contain one or two association sites which are restricted to bond only once. The interactions between particles consist of hard-sphere repulsion and short-ranged directional attraction. We explain how accurate multiple-body correlation information is obtained from a cluster size distribution theory for solvent particles in the bonding region of solute. Then we show that it is feasible to extend the cluster size distribution theory to study a binary mixture of patchy colloids in which the solute can have a single geometrical association site that can bond multiple times or multiple single-bonding sites with different arrangement on the surface. By studying the binary mixture containing Saturn solute with one or two patch solvents, we show that the theory results match well with Monte Carlo simulation for the bonding state at different solute fractions, bonding energies and reduced densities. We also study how phase behavior is affected by the size of the solute Saturn ring, the solute fraction and the ratio of solute-solvent bonding energy to solvent-solvent bonding energy.

Reference:

1.Krejca, Matthias M., Cornell Wüstner, and Werner A. Goedel. 2017. “Pickering Membranes Stabilized by Saturn Particles.” Langmuir 33(41): 10772–81.

2.Bansal, Artee, Walter G. Chapman, and D. Asthagiri. 2017. “Quasichemical Theory and the Description of Associating Fluids Relative to a Reference: Multiple Bonding of a Single Site Solute.” Journal of Chemical Physics 147(12).

3.Bansal, Artee, Arjun Valiya Parambathu, and D Asthagiri. 2017. “Thermodynamics of Mixtures of Patchy and Spherical Colloids of Different Sizes : A Multi-Body Association Theory with Complete.” : 1–30.