title: Molecular dynamics simulations of wetting behavior of water droplets on polytetrafluorethylene surfaces.
abstract: Molecular dynamics simulations are performed to simulate the wetting behavior of nanosized water droplets on flat and pillar polytetrafluorethylene surfaces. The results show that the cutoff of the Lennard-Jones (LJ) potential has a large effect on the simulated value of the contact angle and some suggestions are given on how to choose an appropriate cutoff. On flat surfaces, the contact angle is independent of the size of the water droplet, which was determined by the energy parameters of the LJ potential. Furthermore, on pillar surfaces, two different equilibrium states are present: wetted contact and cross contact. For the wetted contact state, the contact angle increases with increasing droplet size and pillar size within a certain range. However, for the cross contact state, the contact angle and droplet size are uncorrelated, which results from the layering and structuring of molecules after their penetration into the hollows between pillars. However, additional simulations show that the final state depends on the initial geometry and the cross contact state is a metastable wetting state.
authors.affiliation: School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.affiliation: School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Jiadao
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Tianbao
authors.initials: T
authors.lastname: Ma
authors.affiliation: School of Mechanical Engineering, State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
authors.forename: Darong
authors.initials: D
authors.lastname: Chen