The PMF exhibits a minimum and an energy barrier separating the associated and dissociated states, features that arise from the interplay between short-range attraction between NP cores and a longer ranged steric repulsion between the NPs due to their grafts. A 7 th -order PIP was used for fitting this PMF. This involved determination of a total of 9 fitting parameters, which includes 7 linear parameters 𝐶 1 and 2 nonlinear parameters 𝑘 and 𝑥 ' . The inner and outer radii of the switching function were set to 𝑅 7 = 10𝜎 and 𝑅 8 = 12𝜎. The final ) shows excellent agreement with the computed PMF (see also parity plot in Fig. ), capturing well its repulsive shoulder at short distances, its minimum, its energy barrier, and its slow delay over large distances.