Scalable laser micro- and nanostructuring of mould inserts for functional injection-moulded polymer surfaces

Abstract

Functional polymer surfaces with tailored wettability, antibacterial and adhesion properties are increasingly required in medical, packaging and consumer applications. Laser structuring of steel mould inserts followed by injection moulding offers a scalable manufacturing route, but conventional single-beam texturing has limited throughput. Here, we present a selective acceleration strategy that applies different laser techniques to micro- and nanostructuring. Deep microhole drilling was accelerated up to 20-fold by operating an ultrashort-pulse fibre laser at a repetition rate of 1 MHz in single-beam mode. For laser-induced periodic surface structures (LIPSS), line-beam shaping with a spatial light modulator increased productivity by 35-fold, reaching processing speeds above 100 cm$^2$ min$^{-1}$ while retaining sub-micrometre fidelity. Replication experiments with polypropylene (PP), PA66 and ABS confirmed successful transfer of micro- and nanostructures, with PP showing the highest fidelity. Vacuum-assisted injection moulding increased replicated feature height by 56--283 percent. All laser-textured PP surfaces showed higher static water contact angles than the untreated reference, reaching approximately $134^\circ$ in the Wenzel regime. Structured PA66 surfaces reduced bacterial retention by up to 99.8 percent for E. coli and approximately 90 percent for S. aureus. Laser texturing also increased the shear strength of PP joints bonded with a non-optimised adhesive by up to 30-fold. This approach provides a practical, coating-free route to functional polymer components and helps bridge the gap between laboratory laser texturing and industrial injection moulding.