Optimal self-assembly pathways towards colloidal lattices with tunable flexibility

Flexibility governs the many properties of materials and is crucial for the function of proteins and biopolymers. However, how the self-assembly of flexibly bonded particles can lead to larger structures with global reconfigurability is unexplored. We here use a binary colloidal model system equipped with flexible DNA-based bonds to study how regular structures with tunable flexibility can be created through self-assembly. We find that the reconfigurability during lattice growth leads to lattices with square symmetry which are inherently mechanically unstable and hence thermally floppy. By considering the role of size ratio, number ratio, and directionality induced by particle shape, we identify the optimal pathways that maximize the yield and flexibility of these square lattices using a combination of experiments, analytical calculations, and simulations. Our study highlights the crucial role of reconfigurability in systems that are governed by enthalpic and entropic principles, from synthetic to biological, and might be useful for creating materials with novel or reconfigurable properties.