Strategy for Wettability Modification Through High-Aspect Ratio Texturing Using Picosecond Direct Laser Interference Patterning

Direct Laser Interference Patterning (DLIP) has become an industrial-relevant method for microtexturing materials and modifying surface properties.Despite extensive research on DLIP-processed metals for hydrophobicity, the long-term effects of texture geometry on static and dynamic wetting are not yet fully understood.Here, periodic microstructures on stainless steel were fabricated by ps-DLIP to study the effects of texture type, spatial period , and aspect ratio AR on the surface wettability.Line-and cross-like textures with = 6.0, 10.0, and 30.0 m were created using a multi-scan approach to reach ARs of 0.3, 0.6, and 1.0.Wettability was monitored over 220 days by measuring static water contact angle (WCA), contact angle hysteresis (CAH), roll-off angle (Roll-off), and surface free energy (SFE).The results show that smaller spatial periods (6.0 and 10.0 m) favored superhydrophobicity (WCA > 150), with faster stabilization times.In turn, patterns with = 30.0m exhibited a rose-petal effect, with WCA up to 143.4 and CAH > 45.All structured surfaces showed a decrease of the polar component of SFE, in alignment with the observed water-repellency properties.Overall, the period proved to be the dominant factor for increasing the long-term hydrophobicity through DLIP.