Versatile and Functional Surface Patterning of in Situ Breath Figure Pore Formation via Solvent Treatment

Surface patterning of in situ pore formation was studied in this research based on the solvent treatment breath figure (stBF) method. By applying the volatile solvent onto the preshaped polymeric objects under humid conditions, hexagonally arranged pore arrays were formed on the surface efficiently. The stBF method was performed on many different polymeric samples with planar and nonplanar surfaces, and facile pore formation was achieved on these surfaces by conducting the solvent treatment in different ways of dipping, casting, and vapor treatment. The water droplets condensed from the humid air were proved to be the origin of the pore arrays just like the case of classic BF process. The influencing factors including solvent types, surfactant addition, and polymer types were evaluated for their impact on the resultant stBF morphologies. In situ three-dimensional (3D) pore formation was achieved for both macroscopic- and microscopic-sized 3D-structured objects. Chemical patterning of the introduced minor component was also achieved in the stBF pore-forming process with high efficiency and site selectivity. Moreover, the capability of pore formation and erasure with high spatial accuracy using multiple solvent treatments was revealed for the stBF method to make rewritable and hierarchical patterns. Both the selective chemical decoration and rewritable patterning serve as intriguing features of the stBF method. The establishment of the stBF method makes the classic BF process more flexible to practice and less dependent on the external conditions, showing potential for applications such as facile surface patterning with multifunctionality on devices with complex geometry.