Observation of autophobic dewetting on polymer brushes from computer simulation

We propose a method for direct calculation of an effective interface potential from computer simulation. The method allows us to locate the wetting transition, determine its order and calculate the concomitant contact angle of macroscopic drops. We illustrate the method by studying the wetting behaviour of a polymer melt on a brush consisting of chemically identical grafted polymers. At low grafting densities, the melt dewets; at intermediate grafting densities the liquid of free chains wets the brush. On further increasing the grafting density we encounter dewetting (autophobicity). When long-range forces are considered, autophobic behaviour is also observed, but the wetting transition is shifted to larger grafting densities and becomes first order.