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.