The inherent behavior of graphene flakes in water: A molecular dynamics study

Graphene-water interaction has been under scrutiny ever since graphene discovery and realization of its exceptional properties. Several computational and experimental reports exist that have tried to look into the interactions involved, but the response of small graphene to water in a water-based environment requires further investigation. Several computational analyses based on first principle calculations and Molecular Dynamics (MD) have reported graphene to be hydrophobic. Meanwhile, several experimental and MD studies show active interaction between graphene surface and the water molecule. We have, therefore, tested the inherent hydrophobic behavior of small pristine graphene in a water droplet by means of MD simulations. This analysis has been extended to multiple graphene flakes in water and their respective size dependent responses to water droplet. Graphene retreats from water droplet to encapsulate it from the surface. This response was highly reliant on graphene size to water content. Additionally, we also report self-assembly of multilayered graphene in water employing MD simulations, an observation which can be utilized to synthesize such structures cost-effectively by experimentalists. To fully comprehend graphene behavior in water, graphene deformation was analyzed in the presence of water molecules. It was noticed that graphene wrinkled to wrap around water molecules and resisted complete failure, one that is seen in case of the sole graphene sheet. Our work aims to throw light on the behavior of graphene surface and mobility when exposed to comparatively large water content, which can be exploited in numerous applications.