While the scaling at the vapour interface with φ /κ 1/2 is the same for both substrates, the relationship between the entropy difference and φ /κ for the silicon substrate is not as straightforward as that for the graphene substrate (Fig. ). Due to the spacing of the substrate particles (ESI Fig. ), the fluid-substrate potential has more significant lateral corrugations at the silicon interface compared with graphene. This induces a greater dependence of the potential on the in-plane (x, y) coordinates compared to graphene, which is much closer to an "ideal" planar solid surface for which the potential depends only on the z coordinate. Despite the additional variability, the overall scaling behaviour . (The missing points at low κ and high φ formed anisotropic bulk phases and could not be equilibrated on the simulation time scale, and so are not included.) follows the same trend at both substrates, and the fit to all the data was used.