Embossed superhydrophobic polymer surfaces with topological variances

Abstract

In this report, we compare hot and ultraviolet (UV) embossing processes to fabricate hydrophobic surfaces with topological variance. In the hot embossing process, polypropylene was pressurized on a nickel mold with heat, while UV-curable polyurethane acrylate (PUA) was dispensed on the mold followed by UV exposure during the UV embossing process. Cylindrical micro-pillars were successfully replicated using two types of embossing processes with the same mold. The contact angles were then compared at various pillar diameters and with different embossing processes. Although the materials and embossing techniques were different, we achieved a contact angle (CA) enhancement of about 40%. The water contact angle of a transferred substrate, fabricated by the UV embossing process, was 138A degrees. This was much higher than that of flat UV-cured PUA (78A degrees). In addition, we fabricated reverse pillar-shape packing materials for good wettability and then compared the CA values. With the reverse-shape model, we were able to enhance the wettability and decrease the degree of hydrophobicity. This will be beneficial for lipophilic packing materials. This oleophilic characteristic demonstrates enhanced lubrication capabilities as a retort curry packing material.