Sub-microscopic bubbles or nanobubbles attached to a hydrophobic surface are found to be stable and immune to dissolution for a period of hours to days under atmospheric conditions. Typical nanobubble size ranges from tens of nanometers in height to several micrometers in lateral width and, therefore subtend, a high contact angle. The intimate connection between a surface-attached bubble and a hydrophobic surface is that water will not wet a hydrophobic surface.
The air layer entrapped at the solid-liquid interface plays a fundamental role in the functioning of many hydrophobic materials. Underwater surfaces face continuous surface corrosion and microbial accumulation, leading to lower efficiency and shorter lifetimes. The entrapped air layer can inhibit wetting and bacterial adhesion, prevent damage to the surface, and enhance other properties and applications.
Using Molecular Dynamics simulations, the present research aims to unravel the cause of reduced diffusion from the nanobubble surface and the high contact angle subtended by them by considering the interplay of solid, liquid, and gas interaction strengths. The impact of surface nanobubbles and the gas enrichment layer on boundary slip will also be evaluated. Techniques to retain the air layer for a much more extended time will be proposed. It will lead to better design of surfaces employed in underwater applications.