The emergence of supramolecular aggregates from simple microscopic interaction rules is a fascinating feature of complex fluids which, besides its fundamental interest, has potential applications in many areas, from biological self-assembly to smart material design. We here investigate by Monte Carlo simulation the equilibrium structure of a two-dimensional mixture of asymmetric dimers and spheres (disks). Dimers and disks are hard particles, with an additional short-range attraction between a disk and the smaller monomer of a dimer. The model parameters and thermodynamic conditions probed are typical of colloidal fluid mixtures. In spite of the minimalistic character of the interaction, we observe—upon varying the relative concentration and size of the two colloidal species—a rich inventory of mesoscale structures at low temperature, such as clusters, lamellæ (i.e., polymer-like chains), and gel-like networks. For colloidal species of similar size and near equimolar concentrations, a dilute fluid of clusters gives way to floating lamellæ upon cooling; at higher densities, the lamellæ percolate through the simulation box, giving rise to an extended network. A crystal-vapour phase-separation may occur for a mixture of dimers and much larger disks. Finally, when the fluid is brought in contact with a planar wall, further structures are obtained at the interface, from layers to branched patterns, depending on the nature of wall-particle interactions.
Two-dimensional mixture of amphiphilic dimers and spheres: Self-assembly behaviour
Santi Prestipino, Gianmarco Munaò, Dino Costa, Giuseppe Pellicane, Carlo Caccamo; Two-dimensional mixture of amphiphilic dimers and spheres: Self-assembly behaviour. J. Chem. Phys. 14 October 2017; 147 (14): 144902. https://doi.org/10.1063/1.4995549
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