Elucidating the interplay between entropy-driven and patch-mediated bonding in directing nanoscale assemblies†

Abstract

Selective nanoparticle surface patterning presents incredible promise for broadening programmable materials design into a space beyond “close-packed” morphologies. These “patchy” particles impose directional attractions between neighbors that favor the formation of low-coordination, open structures previously inaccessible via their isotropically interacting nanoparticle counterparts. However, unlike patchy colloids, patches on nanoparticles are highly deformable, presenting challenges for their predictive design. Here, we present a multi-faceted approach combining theory and simulation to investigate the underlying forces governing interactions between nanoparticles with flexible patches. We first develop a thermodynamic perturbation theory to fundamentally capture the interplay between patch–patch merging and directional entropic forces in controlling particle organization. We then employ theoretical insights to explicitly consider how monomer geometry synergizes with monomer connectivity in sculpting the equilibrium morphologies for polymeric chains composed of anisotropic monomeric subunits. Theory predictions are then validated using simulations, with excellent agreement across both local and global length scales. Combined, our findings indicate that a large suite of orientational and structural diversity can be attained via precision engineering of how patch–patch and entropic forces between the anisotropic nanoparticles counterbalance each other. These findings on nanoscale patchy interactions offer newer avenues for directing the assembly process of novel polymeric and metamaterials.