The geometric structures and chemical properties of solid substrates are crucial in determining the dynamic behavior of nanobubbles. In this study, we designed a series of nanostructured substrates with alternating hydrophobic and hydrophilic domains based on the thickness and charge dependences of the hydrophobicity of graphene. We then systematically investigated the effects of these nanotrench structures on the dynamic behavior of nanobubbles using molecular-dynamics simulations. The nanotrench structures significantly enhanced the stability of bulk nanobubbles compared to homogeneous, flat graphene, and bulk nanobubble stability increased as the sizes of the hydrophilic domains increased. The mobility paths of the bulk nanobubbles were affected by the positions of the hydrophobic domains. The formation and positions of surface nanobubbles were also controlled by the properties of the nanostructured substrates; the nanobubbles were preferably located on the hydrophobic regions of the substrates. The morphologies of the surface nanobubbles depended on both the sizes of the hydrophobic regions and the degree of hydrophobicity. Under compression strain, the deformed hydrophilic domains of the solid graphene substrate prevented interactions between neighboring surface nanobubbles, resulting in stable nanobubbles. The findings provide insight into the effects of solid substrates on the dynamic behavior of nanobubbles.

• Received 23 May 2019

DOI:https://doi.org/10.1103/PhysRevFluids.4.103603