Understanding the temperature and size dependence of the contact angle of Cu/Si(111): A molecular dynamics study

XF Feng and YJ Mo and YH Zhao and SJ Jiang, COMPUTATIONAL MATERIALS SCIENCE, 150, 222-229 (2018).

DOI: 10.1016/j.commatsci.2018.04.010

Thin film dewetting is a low-cost approach to self-assembling nanoparticles on solid substrates. To pave the way for future dewetting engineering, studies of the parameters that influence the morphology of the final dewetted state are necessary. The dewetted contact angle, which is traditionally used for surface energy evaluation, is of importance in both application and fundamental studies. By introducing a spherical cap model, we found that the contact angle is quantitatively determined by the average surface free energy (SFE) of the nanoparticle (NP), the surface free energy of the substrate and the interfacial free energy (IFE) of the interface. The contact angle, SFE and IFE of the Cu/Si(1 1 1) system were calculated by molecular dynamics. The average SFE of solid Cu NPs and the IFE were found to decrease with increasing temperature and decreasing particle size, which accounted for the decrease of the contact angle with increasing temperature and decreasing particle size. This work suggests an approach to quantitatively determining the contact angle, which is significant for the controlled preparation of metal decorated surfaces.

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