Adsorption on functional surfaces finds application in protective coating of electronic devices, lubricant and adhesives. Relative strength of surface-fluid and fluid-fluid interactions can lead to variety of phase transitions like prewetting, layering and capillary condensation [1].Such phenomena are more important to understand with the emergence of nanotechnology and bottom-up approach [2]. In this work, molecular simulation methodologies are adapted, for the investigation of the first order wetting transitions (thin-thick film transition) on smooth and patterned substrates. Prewetting transition of variable square-well fluid [3] on wide range of weak attractive surfaces is investigated by means of various molecular simulation methodologies. Phase diagram of thin-thick film coexistence of square-well fluid of attractive well diameter λσ =1.5,1.75 and 2.0 in presence of smooth, structure less surface modeled by a square well potential is reported via grand-canonical transition matrix Monte Carlo (GC-TMMC). A systematic investigation is also done to study the effect of surface-fluid interaction, fluid-fluid interaction and long range interactions on the prewetting critical temperature and structural properties. This paper also describes molecular simulation approaches for determining the boundary tension of thin-thick film on a substrate. Boundary tension is found to be sensitive to the surface-fluid affinity and long range behavior of interaction potentials. We also present the prewetting transition and boundary tension of model associating fluids on smooth and patterned surfaces.

References:

1. L. D. Gelb, K. E. Gubbins, R. Radhakrishnan, and M. S. Bartkowiak, Rep. Prog. Phys. 62, 1573 (1999).

2. G. Joachim, J. K. Gimzewski and A. Aviram, Nature 408, 541 (2000).

3. J. K. Singh, G. Sarma and S. K. Kwak, J.Chem. Phys. 128, 044708 (2008).