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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: Focus: Wetting on smooth and rough surfaces: From spreading to superhydrophobicity I

CPP 22.3: Vortrag

Mittwoch, 13. März 2013, 10:15–10:30, H34

The wetting properties of graphene in the light of molecular dynamics simulations — •Frédéric Leroy, Fereshte Taherian-Tabasi, Valentina Marcon, and Nico van der Vegt — Center of Smart Interfaces, TU Darmstadt, Darmstadt, Germany

It has recently been shown that monolayer graphene may serve as a protective coating for metals and nonpolar solid substrates while preserving the wetting properties of these surfaces with respect to water. The question arises as to whether such coating would preserve the wetting properties of all nonpolar surfaces.

To answer this question, the contact angle of water droplets on suspended isolated graphene must be known. Experimental work suggests that graphene may yield a value of the contact angle as high as 127°, whereas other studies suggest a weak enhancement in comparison with the value of 95° on graphite.

We have developed an argumentation supported by molecular dynamics simulations to show that a value of the contact angle of water on graphene cannot exceed 100°. In agreement with recent experimental work, it is thus anticipated that graphene coating is not transparent to the wetting properties of nonpolar subtrates which yield contact angles larger than 100°.

Furthermore, our study leads to the conclusion that the work of adhesion of water on graphene includes a non-negligible entropy contribution. Based on the theory of solvation, we introduce the idea that this entropy contribution is related to the fluctuations in the water-substrate interaction energy.