Peppou-Chapman Sam, Neto Chiara
School of Chemistry, The University of Sydney, NSW 2006, Australia.
University of Sydney Nano Institute, The University of Sydney, NSW 2006, Australia.
Langmuir. 2021 Mar 16;37(10):3025-3037. doi: 10.1021/acs.langmuir.0c02858. Epub 2021 Mar 8.
Lubricant-infused surfaces (LIS) have emerged as an innovative way to combat several modern challenges such as biofouling, ice formation, and surface drag. The favorable properties of LIS are dependent on the presence and distribution of a lubricant layer coating the underlying substrate. Unfortunately, this layer is not indefinitely stable and depletes due to external forces. Here, we study how an air/water interface depletes the lubricant from LIS as a function of lubricant wettability on the substrate by varying the chemistry of both the lubricant and the substrate. The lubricants were chosen to represent some of those most commonly used in the literature (silicone oil, perfluoropolyethers, and mineral oil). We use an optical Wilhelmy plate tensiometer to measure the contact angle of the air/water interface on the LIS as the sample is driven through the air/water interface and contact angle hysteresis as a qualitative measure of lubricant depletion. This data is augmented with quantitative mapping of lubricant thickness using atomic force microscopy (AFM) meniscus force measurements. We find that a thick layer of excess lubricant is always removed in just one dip, regardless of wettability, and that lubricants that do not spread fully on the substrate deplete faster due to their dewetting into droplets. We also find that lubricants that spread onto the air/water interface are more susceptible to depletion. Finally, we investigate the effect of repeated immersions on the properties of liquidlike poly(dimethylsiloxane) (PDMS) chains tethered to glass and find that dynamic contact angles on these surfaces remain constant over several dips and therefore their low hysteresis is unlikely due to unbound polymer.
注入润滑剂的表面（LIS）已成为应对生物污染、结冰和表面阻力等多种现代挑战的创新方法。LIS的优良性能取决于覆盖在底层基材上的润滑层的存在和分布。不幸的是，该层并非无限稳定，会因外力而耗尽。在此，我们通过改变润滑剂和基材的化学性质，研究空气/水界面如何根据润滑剂在基材上的润湿性从LIS中耗尽润滑剂。所选用的润滑剂代表了文献中最常用的一些润滑剂（硅油、全氟聚醚和矿物油）。当样品穿过空气/水界面时，我们使用光学威尔海姆板张力仪测量空气/水界面在LIS上的接触角，并将接触角滞后作为润滑剂耗尽的定性度量。此数据通过使用原子力显微镜（AFM）弯月面力测量对润滑剂厚度进行定量映射得到补充。我们发现，无论润湿性如何，仅仅一次浸入就总会去除一层厚厚的过量润滑剂，并且那些不能在基材上完全铺展的润滑剂由于其脱湿成液滴而耗尽得更快。我们还发现，铺展在空气/水界面上的润滑剂更容易耗尽。最后，我们研究了反复浸入对连接到玻璃上的类液体聚二甲基硅氧烷（PDMS）链性能的影响，发现这些表面上的动态接触角在几次浸入过程中保持恒定，因此它们的低滞后不太可能是由于未结合的聚合物所致。
