Effective formation of hierarchical wavy shapes using weak photopolymerization and gradual thermal curing process

• Hierarchical wrinkles are common in nature and have rich surface characteristics.
• We propose a simple and effective way of fabrication of hierarchical wrinkling structures.
• 10–20 μm line width wrinkles on relatively large wrinkles of 400–500 μm in line width.
• By using the hierarchical wrinkles, about 55% increase of contact angle.

We propose a simple method to generate hierarchical wrinkles on a single-layered substrate by using a weak photopolymerization and a thermal curing process. Rough and relatively large-scale wrinkles having 300–500 µm width sizes are fabricated by a repetitive volume dividing (RVD) method, which is known as one of the effective processes to generate wrinkle patterns in a large area. After generation of the primary wrinkles that are weakly polymerized, microscale wrinkles with width of 10–20 µm on the large-scale ridges are formed spontaneously by room-temperature-based thermal curing. We rationalize the mechanism for the generation of hierarchical abnormal shaped structures and quantify the experimental findings by a parametric study. Through this work, we show the relevance of these structures for use in diverse applications such as surface modification for wettability control and antifouling.