Assembling colloidal microparticles with directional bonding into desired colloidal superlattice have been a long-standing challenge in the field due to the complexity of selective functionalization of particle surface and poor tunability of interactions. Herein we demonstrate that selective depletion interaction can be exploited to engineer the directional bonding and assembly of colloidal microparticles made of hybrid materials. We discover selective crystallization of spheres made of different materials in the presence of specific depletants. Inspired by that, we fabricate triblock biphasic colloids with various aspect ratios to achieve regioselective bonding and assembly. Without any surface treatment, we can assemble them into various colloidal superstructures and superlattices with polymorphic formation. Furthermore, by switching the depletion condition, we observe a new scenario of colloidal chains and membranes featuring different site-specific interaction. Our method requires no tedious surface functionalization to realize directional interaction, which can be further adopted for other programmable colloidal assemblies and colloidal materials processing.

Switchable regioselective assemble of triblock microparticles based on surface material recognition

2019 Fall National Meeting

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