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Abstract
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We present a detailed model to study the
nucleation of triblock Janus particles from solution. The Janus
particles are modeled as cross-linked polystyrene spheres
whose poles are patched with sticky alkyl groups and their
middle band is covered with negative charges. To mimic the
experimental conditions, solvent, counterions, and a substrate,
on which the crystallization takes place, are included in the
model. A many-body dissipative particle dynamics simulation
technique is employed to include hydrodynamic and manybody
interactions. Metadynamics simulations are performed to
explore the pathways for nucleation of Kagome and hexagonal
lattices. In agreement with experiment, we found that
nucleation of the Kagome lattice from solution follows a
two-step mechanism. The connection of colloidal particles through their patches initially generates a disordered liquid network.
Subsequently, orientational rearrangements in the liquid precursors lead to the formation of ordered nuclei. Biasing the
potential energy of the largest crystal, a critical nucleus appears in the simulation box, whose further growth crystallizes the
whole solution. The location of the phase transition point and its shift with patch width are in very good agreement with
experiment. The structure of the crystallized phase depends on the patch width; in the limit of very narrow patches strings are
stable aggregates, intermediate patches stabilize the Kagome lattice, and wide patches nucleate the hexagonal phase. The scaling
behavior of the calculated barrier heights confirms a first-order liquid-Kagome phase transition.
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