To understand the mechanisms underlying the above results, we quantified the distribution of cations on different site types ("surface" vs "bulk") in the multiparticle system, corresponding to the different types of regions within the space between two nanoparticles (Figure ). Explicitly, as illustrated in Figure , surface sites represent the region near the nanoparticle where the grafted anions are present, and bulk sites represent the region away from the surface with significant solvent presence.