Influence of substrate strength on wetting behavior

We examine the evolution of prewetting phase behavior with substrate strength for a model Lennard-Jones system, which consists of monatomic particles interacting with a single structureless surface. Grand canonical transition matrix Monte Carlo simulation is used to characterize surface phase behavior for several wall strengths. Our results indicate that both wetting and prewetting critical temperatures increase with decreasing wall strength, with the former increasing at a faster rate than the latter. The two curves appear to meet at the critical temperature of the bulk fluid at nonzero substrate strength. Overall, prewetting transitions are found within a triangular-shaped region within the temperature-wall strength plane, bound by wetting and prewetting critical lines and a series of layering/crystallization transitions at low temperature. The interfacial tension is calculated along each saturation line, from which we deduce the latent heat of the prewetting transition. Several corresponding states ideas are also discussed. We examine the ability of the phenomenological model of Cheng and co-workers [Cheng, E.; Cole, M. W.; Saam, W. F.; Treiner, J. Phys. Rev. Lett. 1991, 67, 1007. Cheng, E.; Cole, M. W.; Saam, W. F.; Treiner, J. Phys. Rev. B 1993, 48, 18214] to predict accurately the evolution of wetting temperature with substrate strength. In addition, we consider the extent to which select prewetting data from different wall potentials collapse when scaled by either wetting or prewetting critical point properties.