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Abstract
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The self-assembly of triblock Janus particles is simulated from a fluid to 3D open
lattices: pyrochlore, perovskite, and diamond. The coarse-grained model ex-
plicitly takes into account the chemical details of the Janus particles (attractive
patches at the poles and repulsion around the equator) and it contains explicit
solvent particles. Hydrodynamic interactions are accounted for by dissipative
particle dynamics. The relative stability of the crystals depends on the patch
width. Narrow, intermediate, and wide patches stabilize the pyrochlore-, the
perovskite-, and the diamond-lattice, respectively. The nucleation of all three lat-
tices follows a two-step mechanism: the particles first agglomerate into a com-
pact and disordered liquid cluster, which does not crystallize until it has grown
to a threshold size. Second, the particles reorient inside this cluster to form
crystalline nuclei. The free-energy barriers for the nucleation of pyrochlore and
perovskite are ≈10 k B T, which are close to the nucleation barriers of previously
studied 2D kagome lattices. The barrier height for the nucleation of diamond,
however, is much larger (>20 kB T), as the symmetry of the triblock Janus parti-
cles is not perfect for a diamond structure. The large barrier is associated with
the reorientation of particles, i.e., the second step of the nucleation mechanism.
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