Patterned Hydrophilic Patches on Slippery Surfaces with Anticounterfeit Applications

From conventional liquid repellent performance to manipulating liquid motion on a planar substrate, “slippery surfaces” with designed liquid-confined patterns (patterned slippery surfaces) have shown great success in many fields including microfluidic devices, microarray formation, and liquid guiding technologies. However, the fabrication of patterned slippery surfaces is not simple, and most of these fabrication methods involve complex surface chemical modification and multiple steps, significantly reducing the practicality of patterned slippery surfaces. In this study, a facile and simple approach to generate patterned slippery surfaces without complex chemical functionalization is demonstrated. A superhydrophobic base film is produced via layer-by-layer assembly of branched polyethylenimine (BPEI) and Nafion, a perfluorinated polyelectrolyte, in methanol. After that, a concentrated BPEI patterning solution is applied to the surface to create hydrophilic regions. As these hydrophilic domains have a stronger affinity to aqueous media than to the lubricant, a slippery surface with a hydrophilic pattern which can constrain liquid motion is obtained after infiltrating lubricant in the surface. This approach not only offers an efficient way to prepare patterned slippery surfaces but also provides versatility for different applications such as transparent surface patterning and liquid manipulation. Moreover, the flexibility of incorporating a solvatochromic dye into the patterning solution has introduced the possibility for the use of patterned slippery surfaces in anticounterfeiting technology.