Interfacial depletant partitioning for lattice-tunable colloidal assembly

The depletion force is a perfect example of entropic action where electron binding is not involved to assemble matter. Here we demonstrate that depletion forces can also be used to modulate dimensional changes in a colloidal lattice. The modulation is possible by introducing the concept of depletant partitioning, where depletants can freely penetrate semipermeable colloids during self-assembly. The reversible and programmable absorption of depletants gives rise to the emergence of a dynamic depletion potential that stabilizes colloidal assemblies. The range energies and amplitudes of the colloidal lattice variations are modulated by the temperature dependent concentration and affinity of depletants in solution. This colloidal platform exhibits a finely tunable self-reinforcing effect where rising temperature fortifies the expansion of colloidal superlattices, creating future avenues for assembly and action in colloidal-based materials. Colloidal systems have the potential to mimic complex self-assembly processes found in nature, which can lead to innovative materials with tailored properties. This study introduces an approach using depletant partitioning to dynamically modulate the size and stability of colloidal assemblies through temperature changes, achieving finely tunable lattice variations and expanding the possibilities for colloidal-based materials.