Molecular dynamics simulation of the spreading of the nanosized droplet on a graphene-coated substrate: the effect of the contact line forces

ABSTRACT

Surface characteristics of graphene have an important impact on its performance. Substantial attention has been devoted to studying the static wetting behaviour of a graphene-coated substrate with little attention to the dynamic wetting behaviour. The impact of contact line forces (CLFs) on the droplet-spreading process has not been revealed completely yet. A series of molecular dynamics (MD) simulation is performed to investigate the spreading process of the water droplet on the graphene-coated substrate in this research. The increase of interaction potential parameter between substrate and water droplet makes the spreading radius getting bigger and the final static contact angle smaller. Apart from that, the higher hydrophilicity of underlying substrate can lead to the greater averaged forces of atoms near contact line. CLFs correlate well with the variation of kinetic energy of water molecules located in the contact line region. Surface tensions of water droplets on graphene-coated substrates are also examined. The liquid-vapour and solid-vapour surface tensions are constant. An increase in the surface tension of liquid-solid lead to the increase of balanced contact angles of water on the substrate. The results are useful for understanding the effect of CLFs on the dissipation of kinetic energy of water molecules.

KEYWORDS:

• Graphene
• contact line forces
• wettability
• MD simulation

ORCID

Bai Qingshun http://orcid.org/0000-0002-8626-4431

Additional information

Funding

This research is supported by National Natural Science Foundation of China [grant numbers 51535003, 51575138, 51775146].