The formation of a hydrophobic bond implies that the interfacial ligands bend and open to expose their hydrophobic stretches. As a result of dimerization, the terminal groups of the MUS ligands are pushed away from the NP-NP interface and compacted in non-contact regions. Consequently, a lower net volume is available to the ligands around the NPs, and a higher surface charge density is present in non-contact regions. To quantify this effect, we calculated the hydrophobic area exposed by the surface of the NPs, before and after dimerization. In analogy with the solvent-accessible-surface-area (SASA), we will refer to this hydrophobic area as the hydrophobic SASA (see SI for further details).