Fabrication of a Large-Area Hierarchical Structure Array by Combining Replica Molding and Atmospheric Pressure Plasma Etching.

A novel approach to produce a large-area hierarchical structure array is presented. The method combines replica molding and atmospheric pressure plasma (APP) etching processes. Liquid blends consisting of siliconized silsesquioxane acrylate (Si-SSQA), polyethylene glycol dimethacrylate (PEGDMA), and photoinitiator are used as roughness formable materials during APP etching. Microstructures composed of the Si-SSQA/PEGDMA mixtures are fabricated by replica molding. Nanoroughness is realized on the microstructures by argon/oxygen (Ar/O₂) APP etching in air. The nano­roughness on molded microstructures is efficiently controlled by varying the weight ratio of Si-SSQA to PEGDMA and the etching time. The hierarchical structures fabricated by combining replica molding and Ar/O₂ APP etching show superhydrophilicity with a long-term stability, resulting in the formation of hydroxyl-terminated silicon oxide layer with the reorientation limit. On the other hand, the hierarchical structures treated with a perfluorinated self-assembled monolayer (SAM) show increased the water contact angles of up to 161° depending on the morphology of the hierarchical structures. The increment of water contact angles is consistent with increment of the nano-/microroughness of hierarchical structures. [ABSTRACT FROM AUTHOR]