Design rules of two-dimensional colloidomer folding

Folding of a protein into a final structure is a reversible process governed by the amino-acid sequence of the protein backbone. Similarly, through the control of particle-particle interactions, colloidomers — flexible chains of colloidal particles [1] — can assemble into well-defined structures, allowing us to exploit folding as a design strategy for self-assembly. Here we study the effect of switching on/off nearest-neighbor and next-nearest neighbor interactions on the folding of a colloidomer chain. Inspired by proteins, we develop an algorithm that selects unique folds of a particulate chain in two dimensions by searching in sequence, particle species and interaction space [2]. For an alternate sequence of two particle species, i.e., ABABAB…, we find 10 unique solutions for chain sizes ranging from N = 6 to N = 12 particles. We show that some of the solutions rely on the hierarchy of interactions. We use experiments and simulations to verify the existence of these solutions and characterize their yield. Our study suggests design rules for interactions along the chain leading to assembly of structures with a particular geometrical motif. This strategy opens the door to the design of novel supra-colloidal building blocks.