Influence of roughness achieved by periodic structures on the wettability of aluminum using direct laser writing and direct laser interference patterning technology

The fabrication of periodic microstructures on pure aluminum is studied in this work. Triangular and pillar-like structures are manufactured using nanosecond pulsed direct laser writing (DLW) and picosecond pulsed direct laser interference patterning (DLIP), respectively. By varying the process parameters (laser fluence, pulse to pulse overlap, pattern size and geometry) structures with different depths and corresponding roughness parameters are produced. Finally, the influence of the various resultant morphological parameters on the wettability properties of the fabricated structures is investigated by means of static contact angle measurements. Two different behaviors are observed with respect to the long term wetting properties depending on the used laser method. The topography of the treated surfaces is characterized using confocal microscopy and scanning electron microscopy, while contact angle measurements are performed with a drop shape analyzer. Surface chemistry is analysed by X-Ray photoelectron spectroscopy.