Novel Hollow Re-entrant Structures Improving Hydrophobicity of Metal Surfaces

Abstract

Re-entrant structures have drawn increasing attention because of their hydrophobicity. However, it is very difficult to manufacture re-entrant structures at the micron scale on metal surfaces. In this study, we designed and manufactured novel hollow re-entrant structures employing laser ablation and electrodeposition technology. This designed hollow re-entrant structure on metal surfaces has been fabricated successfully, which has high processing efficiency and good repeatability. The morphology and size of the hollow re-entrant structures were characterized. We found that the hydrophobic performance of hollow re-entrant structures was improved after being in the atmosphere for 3 days. After electrodeposition, the static contact angle was 133°. However, after being placed in the atmosphere for 3 days, the static contact angle was 140.4°, which is 5.2% higher than that after electrochemical deposition. We explained the cause of this phenomenon. The change of element content on the surface of hollow re-entrant structures was used to indicate the formation of metal oxide. After being in the atmosphere for 3 days, oxygen content increased by 0.4%. The metal surfaces with hollow re-entrant structures have a broader application prospect.