Photo-Polymerization Induced Hierarchical Pattern via Self-Wrinkling

Hierarchical patterns are widely found on the biological skins in nature and can provide unique functions to surfaces such as wettability, optical, and adhesive properties. Herein, a facile and robust strategy to generate the self-wrinkling pattern on the surface of the photo-curing coating is proposed, which comprises a crosslinking monomer, photoinitiator, and fluorinated copolymer as additive. The fluorinated copolymer, which contains fluorocarbon chains possessing low surface-energy, tertiary amine as coinitiator, and anthracene in the side chain, can self-assemble to the top layer for constructing the gradient photo-crosslinking system. Upon the irradiation of ultraviolet (UV) light, the mismatch of shrinkage caused by the gradient photo-crosslinking leads to the formation of wrinkles, the morphology of which can be regulated by monomer proportion, the content of fluorinated copolymer, and the thickness of the film. Taking the spatiotemporal advantages of light, the hierarchical patterns of wrinkle are generated by programmed exposure with photomask, which has potential applications in anti-counterfeiting and encapsulation of light-emitting diode (LED) chip for displaying. This strategy provides a rapid and universal alternative method to fabricate a hierarchical pattern of the surface.