Wetting Behaviour of Thin Diblock Films

We study the wetting behaviour of a thin diblock copolymer film deposited on a solid substrate. Near the wetting edge of a monolayer we find that the chains may be oriented parallel to the surface, whereas in the layer interior they are perpendicular to it. These two orientations give rise to two wetting transitions. Various edge configurations are predicted, depending on the surface tensions. We find that bending/splay terms are only ever important near the wetting edge where they fix the chain orientation parallel to the wetting edge. We also estimate the line tension associated with the wetting edge. This quantity will control the growth of droplets