Phoretic self-assembly of active colloidal molecules

We simulate the self-assembly of active colloidal molecules from binary mixtures of spherical particles using a Brownian dynamics algorithm.These particles interact via phoretic interactions,which are determined by two independently tunable parameters,surface activity and surface mobility.In systems composed of equal-size particles,we observe the formation of colloidal molecules with well-defined coordination numbers and spatial arrangement,which also display distinct dynamic functions,such as resting,translating,and rotating.By changing the size ratio to 2:1 between the two species,we further observe the formation of colloidal molecules with new structures arising from breaking the size symmetry.By tuning the mutual interactions between the smaller species via their surface mobility,we are able to control their spacing as well as the coordination number of the colloidal molecules.This study highlights the importance of tuning surface parameters and size asymmetry in controlling the structure and the active dynamics of colloidal molecules.