Laser Ablation and Chemical Oxidation Synergistically Induced Micro/Nano Re-entrant Structures for Super-Oleophobic Surface with Cassie State

Generally, re-entrant structures are a key part of fabricating superoleophobic surfaces, and this structure appears in almost all kinds of published research articles regarding superoleophobicity. However, the application of related fabrication methods is usually too complex and costly in real practice. In this paper, we present a simple method to generate micro-cauliflower structures, which work as re-entrant structures in microcone arrays, to promote the formation of superoleophobic surfaces. The heating process after alkali-assisted surface oxidation is the main reason for the appearance of a micro-ball structure, and the oxidation time can influence the size of the micro-ball. To the best of our knowledge, the influence of the heating process after alkali-assisted surface oxidation on the birth of the micro-ball structure is seldom researched. A low-surface-energy treatment was also analyzed in influencing the size of the re-entrant structure and its relative wettability. Droplets of 5 μl of n -decane show contact angles of 155 ± 1°on the as-prepared superoleophobic surface, and air pockets can be clearly seen underneath, indicating a stable Cassie contacting state and a promising application value in the near future.