  Tribological phenomena are governed by combined effects of material
properties, topology and surface-chemistry. We study the interplay of
multiscale surface structures with molecular-scale interactions towards
interpreting static frictional interactions at fractal interfaces. By
spline-assisted-discretization we analyse asperity interactions in pairs of
contacting fractal surface-profiles. For elastically deforming asperities,
force analysis reveals greater friction at surfaces exhibiting higher
fractality, with increasing molecular-scale friction amplifying this trend.
Increasing adhesive strength yields higher overall friction at surfaces of
lower fractality owing to greater true-contact-area. In systems where
adhesive-type interactions play an important role, such as those where
cold-welded junctions form, friction is minimised at an intermediate value of
surface profile fractality found to be around 1.3 to 1.5. Results have
implications for systems exhibiting evolving surface structures.
