Surface Wettability Manipulation of Nonmetallic and Metallic Liquids on CVD Diamonds with Varying Adhesion Forces

Diamonds are widely utilized in industrial applications owing to their exceptional thermal conductivity, mechanical hardness, and chemical inertness. To facilitate effective interactions with both nonmetallic and metallic liquids under specific operational conditions, it is imperative to adjust the surface energy levels of diamond. In this study, we employed UV-ozone and hydrogenated plasma treatments to modify the surface energy of diamond with a (100) crystallographic orientation. We assessed the surface wettability of the functionalized diamonds using the sessile drop method, examining their interactions with bulk liquids that exhibited varying surface tensions, ranging from 0.022 to 0.48 N/m. We quantitatively assessed how the surface energy levels of both O-terminated and H-terminated diamond affected their wettability with various nonmetallic and metallic liquids. In addition, we developed a computational fluid dynamics model to numerically analyze the influence of the diamond’s surface energy on the droplet configurations of these bulk liquids. Furthermore, we investigated the long-term effects of surface oxidation through UV-ozone treatment by exposing diamond to ambient air over a span of 100 hours. Our results indicated that the hydrophobic recovery phenomenon significantly impacted the surface wettability of O-terminated diamonds when interacting with polar liquids. This work introduces a unified experimental-computational approach to map wettability transitions of nonmetallic and metallic liquids on diamonds, offering insights into the role of surface energy in wetting-state design.