Tulip-Shaped Pattern Imprinting for Omni-Phobic Surfaces Using Partially Cured Photopolymer

Abstract

Functional films with hydrophobic, oleophobic, anti-fouling, anti-icing, anti-bacterial and low reflectance properties can be produced by patterning nano- or micro-structures on films via nano imprint lithography. Here, an omni-phobic surface showing both hydrophobicity and oleophobicity was obtained without chemical surface treatment by increasing the surface roughness and deforming the pattern morphology using only nano imprint lithography and the oxygen-inhibited curing properties of polyurethane acrylate (PUA) resin. A tulip-shaped pattern imprinting process was designed in which microscale patterns were fabricated using a porous polydimethylsiloxane (PDMS) mold with high oxygen transmission. During ultraviolet (UV) curing, a curing inhibiting layer was formed by reaction with oxygen. Next, a PDMS pad was used for the pressurized curing of the curing inhibition layer to modify the micro scale structures. Finally, final curing of the deformed pattern was performed using ultra high-power UV light. The deformation of the pattern into tulip-like shapes with increased surface roughness was confirmed by microscopy, and contact angle measurement was performed to confirm omni-phobicity. The final cured imprinted samples showed water and oil contact angles reaching 169.2° and 115°, respectively; thus, the omni-phobic surface could be demonstrated by a tulip-shaped pattern imprinting process.