Femtosecond laser processing of steel template for mass production of superhydrophobic polyethylene film

The development of polymer film with superhydrophobicity and low adhesion is critical for high-end markets such as packaging, biomedical, and cosmetics. This study explored the efficient fabrication of superhydrophobic polyethylene (PE) film by duplicating the microgrid structure from a femtosecond (fs) laser-processed steel template. First, the steel template with different spacing and microgrid structures was prepared by fs laser, and then the superhydrophobic PE film was hot-processed on the template. Thus, numbers of air pockets in the spacing of 60 μm and villus-like protrusion at the node were produced on the PE film surface. The duplicated microstructure induced a static contact angle (SCA) of 157.9° and a sliding angle (SA) of 7.9°, indicating significantly low adhesion and excellent self-cleaning ability. Furthermore, it exhibited an SCA exceeding 150° and an SA below 30° to viscous liquids such as cola, milk, coffee, and yogurt. In the meantime, the superhydrophobic PE film demonstrated an extended icing time from 90 s to 196 s in the anti-icing test and reduced ice adhesion strength from 26.201 kPa to 21.1 kPa. During the ice melting process, the superhydrophobic PE surface exhibits an ice-repellent effect, which enables the ice-water mixture to slip off rapidly at the 70th s of ice melting. In addition, the PE film maintained good water repellency after soaking in acidic, neutral, and alkaline solutions.