Wetting behavior of MoS₂ thin films

The water contact angle (${\theta }_w$) measurements have been carried on MoS₂ thin films grown by chemical vapor deposition. An increase in ${\theta }_w$ by almost 70% compared to the bare quartz substrate indicates that MoS₂ can efficiently screen the van der Waals interaction of the underlying substrate with water. The ${\theta }_w$ increases with the number of MoS₂ layers. The observed advancing and receding ${\theta }_w$ of 98.0° and 55.40°, respectively indicates a significant contact angle hysteresis. Neumann's equation of state theory is used to determine the surface free energy of MoS₂ layer and is estimated to be about 39 mJ m⁻². (paper)