Improving antifouling functions of titanium alloys by robust slippery liquid-infused porous surfaces with tailored multiscale structures

The practical applications of delicate micro/nanostructures with extraordinary functions are severely limited by the insufficient mechanical stability. To address this challenge, the incorporation of protective "armor" for fragile micro/nanostructures has emerged as a promising approach to endow mechanical robustness. In this study, we have employed the concept of "armor" by fabricating honeycomb concave cells on surfaces of large-size Ti-6Al-4V (TC4) plates using screen-printed etching, followed by anodic oxidation to establish an array of multiscale structures. A new type of slippery liquid-infused porous surface (TC4-SLIPS) has been further produced by the infusion of lubricants into the exquisite multiscale structures. The results show that the tailored multiscale structures enhance stabilization of the lubricant layer, which can retain surface hydrophobicity (WCAs similar to 104.8 degrees) even after artificial seawater washout for 30 days. Moreover, the multiscale structures improve resistance to external mechanical abrasion, resulting in the robust hydrophobic nature of the SLIPS. Attractively, TC4-SLIPS can effectively inhibit the adhesion and proliferation of Pseudoalteromonas bacteria, and thereby prevent the formation and proliferation of bacterial biofilms. Therefore, the state-of-the-art TC4-SLIPS with multiscale structures has shown significance for the long-term antifouling of titanium alloys in practical applications.