Hossein Eslami

A realistic model of triblock Janus particles, in which a cross-linked polystyrene sphere capped at the poles with hydrophobic n-hexyl groups and in the equatorial region with charges, is used to study the phase equilibrium boundaries for stabilities of quasi-two-dimensional liquid, Kagome, and hexagonal phases. The pole patches provide interparticle attraction, and the equatorial patches provide interparticle repulsion. The self-assembly has been studied in the presence of solvent, charges, and a supporting surface. An advanced sampling many-body dissipative particle dynamics simulation scheme, with the inclusion of many-body and hydrodynamic interactions, has been employed to drive the system from liquid to solid phases and vice versa. Our calculated phase diagrams indicate that, in the limit of narrow pole patch widths (opening angle ?65°), the Janus particles self-assemble to the more stable Kagome phase. The entropy-stabilized Kagome lattice is more stable than the hexagonal phase at higher temperatures. Increasing the pressure stabilizes the denser hexagonal versus the Kagome lattice. Enlarging the pole patch width (varying the opening angle from 65° to 120°) promotes the bonding area and, hence, energetically stabilizes the close-packed hexagonal versus the open Kagome lattice. A comparison with previous calculations, using the Kern?Frenkel potential, has been done and discussed.