Gibbs Adsorption Impact on a Nanodroplet Shape: Modification of Young–Laplace Equation

Mykola Isaiev (1, 2) , Sergii Burian (1) , Leonid Bulavin (1) , William Chaze (2) , Michel Gradeck (2) , Guillaume Castanet (2) , Samy Merabia (3) , Pawel Keblinski (4) , Konstantinos Termentzidis (2)

1 Taras Shevchenko National University of Kyiv
2 LEMTA - Laboratoire d'Energétique et Mécanique Théorique et Appliquée
3 ILM - Institut Lumière Matière [Villeurbanne]
4 Materials Science and Engineering Department

We present an efficient technique for the evaluation of the Gibbs adsorption of a liquid on a solid substrate. The behavior of a water nanodroplet on a silicon surface is simulated with molecular dynamics. An external field with varying strength is applied on the system to tune the solid–liquid interfacial contact area. A linear dependence of droplet’s volume as a function of the contact area is observed. We introduce a modified Young−Laplace equation to explain the influence of the Gibbs adsorption on the nanodroplet volume contraction. Fitting of the molecular dynamics results with the analytical approach allows us to evaluate the number of atoms per unit area adsorbed on the substrate, which quantifies the Gibbs adsorption. Thus, a threshold of a droplet size is obtained, for which the impact of the adsorption is crucial. For instance, a water droplet with 5 nm radius has 3% of its molecules adsorbed on silicon substrate, while for droplets less than 1 nm this amount is more than 10%. The presented results could be beneficial for the evaluation of the adsorption impact on the physical–chemical properties of nanohybrid systems with large surface-to-volume ration.

Keywords: Liquids; Adsorption; Layers; Molecules; Silicon

Domains: Physics [physics]; Condensed Matter [cond-mat]; Materials Science [cond-mat.mtrl-sci]

Mykola Isaiev, Sergii Burian, Leonid Bulavin, William Chaze, Michel Gradeck, et al.. Gibbs Adsorption Impact on a Nanodroplet Shape: Modification of Young–Laplace Equation. Journal of Physical Chemistry B, 2018, 122 (12), pp.3176 - 3183. ⟨10.1021/acs.jpcb.7b12358⟩. ⟨hal-01832695⟩