Femtosecond Laser‐Engineered Molds for Long‐Term Stable Superhydrophobic Polydimethylsiloxane (PDMS) Surfaces

Abstract Surface functionalization is essential for improving polymer properties like wettability and wear resistance. Polydimethylsiloxane (PDMS) is widely used due to its flexibility, biocompatibility and ease of fabrication. Soft lithography—based on molding and replication—is the most common approach to tailor its wettability, but producing high‐quality molds remains complex and time‐consuming, calling for faster, cost‐effective and reproducible alternatives. In this work, a novel femtosecond laser‐based technique is presented for the rapid and precise fabrication of aluminum molds for PDMS replication. By tuning hatch distance and scan number as key process parameters, the resulting surface morphology of the PDMS replicas is controlled. The samples are characterized morphologically and by profilometry; the reproducibility of the laser‐engraved molds and the effect on the final PDMS surfaces is assessed, alongside wettability measurements as a function of the processing parameters, achieving superhydrophobic behavior under optimized conditions. Long‐term testing over 4 months confirmed the stability and durability of the surface properties, highlighting their potential for applications in self‐cleaning systems, droplet‐based microfluidics and biomedical devices.