Confinement Effects in Cooperative Self-Assembly of Patchy Particles and Spherical Colloids.

A comprehensive computational investigation of the self-assembly behavior of two-component mixtures composed of patchy nanoparticles (PNPs) and isotropic nanoparticles (INPs) was conducted. Both bulk systems (in two and three dimensions) and confined systems subjected to seven distinct external fields were examined, including nonselective fields and fields preferentially interacting with one component. In two-dimensional (2D) systems, density-dependent organization into square or triangular lattices was observed. The triangular phase exhibited two distinct morphologies depending on mixture composition, with PNPs forming a Kagomé sublattice in one of them. In three-dimensional (3D) systems, a fcc crystalline structure was identified both in the bulk and under confinement. This structure consists of two interpenetrating sublattices: a bcc lattice formed by PNPs and a sc lattice formed by INPs. Furthermore, the growth direction and stacking sequence of the fcc crystals were found to depend on the strength and selectivity of the external field. These results provide insight into the controlled design of complex colloidal architectures through confinement and external field modulation.