Surface Functionalization for a Nontextured Liquid-Infused Surface with Enhanced Lifetime.

Liquid-infused surfaces (LISs) are a new class of self-cleaning surfaces having superior properties compared to other self-cleaning surfaces. One challenge regarding these is the eventual washing away or drainage of the lubricant, limiting their longevity. Presented here is a surface functionalization strategy to compatibilize the lubricant and surface, enhancing the ability of the lubricant to remain on the surface even during washing. The strategy used here is the grafting of a layer of polydimethylsiloxane (PDMS) to the surface, which stabilizes a layer of silicone oil. The effectiveness of this layer is studied as a function of PDMS molecular weight. The stable liquid layer can exist even in the absence of texture on the surface that is generally used to "lock" the lubricant in place. This strategy is shown to be effective on both flat and textured surfaces. One advantage of a flat surface is that the composite liquid/solid surface can be studied using optical techniques such as ellipsometry, which are difficult to employ in the presence of a rough solid surface. This method of surface compatibilization shows an enhanced lifetime when used on textured surfaces as well. This is a promising strategy for the enhanced longevity of LISs required for real-world applications.