M. J. de Ruijter

Effect of temperature on the dynamic contact angle

Abstract The temperature influence on the contact angle relaxation of partially wetting drops is measured for squalane on poly(ethyleneterephthalate). The results are analyzed with the molecular kinetic model, a hydrodynamic model and a model that combines the two previous ones. For each temperature all three approaches can fit our experiments well, but only the molecular kinetic approach leads to physically meaningful parameters. The associated free energy of wetting, introduced by that approach, increases weakly with temperature.

Droplet spreading: a microscopic approach

Abstract It is shown that the technique of molecular dynamics allows a complete study of the dynamics of droplet spreading at the microscopic scale, for both complete and partial wetting regimes. In particular, we are able to study, in great detail, the net fluxes inside the drop during spreading. We confirm that at the molecular level, the mechanism of spreading can be viewed as a competition between a surface tension driving force and friction between the liquid and solid atoms. This result supports the molecular kinetic theory of wetting as well as the de Gennes–Cazabat model of spreading.

The Dynamics of Spreading at the Microscopic Scale

By Molecular Dynamics simulations, we study the dynamics ofspreading. Our numerical data are in agreement with experimentalobservations and allow to describe the microscopic details of the mechanism,in particular how the liquid molecules reach the solid substrate. Theseresults support the validity of the de Gennes-Cazabat model describing thespreading as a competition between the driving force due to the wallattraction and the friction between the liquid molecules and the solidatoms.

Droplet spreading: a tool to characterize surfaces at the microscopic scale

Abstract We show here how model systems involving large-scale molecular dynamics simulations can be used to study the dynamics of spreading. The results strongly support the validity of the molecular–kinetic model of friction with the solid. This means that, by studying the dynamics of spreading of a sessile drop, we can deduce microscopic characteristics of the surface.