Lee Choongyeop, Choi Chang-Hwan, Kim Chang-Jin Cj
Mechanical and Aerospace Engineering Department, University of California, Los Angeles (UCLA), California 90095, USA.
Phys Rev Lett. 2008 Aug 8;101(6):064501. doi: 10.1103/PhysRevLett.101.064501. Epub 2008 Aug 5.
We study experimentally how two key geometric parameters (pitch and gas fraction) of textured hydrophobic surfaces affect liquid slip. The two are independently controlled on precisely fabricated microstructures of posts and grates, and the slip length of water on each sample is measured using a rheometer system. The slip length increases linearly with the pitch but dramatically with the gas fraction above 90%, the latter trend being more pronounced on posts than on grates. Once the surfaces are designed for very large slips (>20 microm), however, further increase is not obtained in regular practice because the meniscus loses its stability. By developing near-perfect samples that delay the transition from a dewetted (Cassie) to a wetted (Wenzel) state until near the theoretical limit, we achieve giant slip lengths, as large as 185 microm.
我们通过实验研究了纹理化疏水表面的两个关键几何参数（间距和气体分数）如何影响液体滑移。这两个参数在精确制造的柱体和格栅微结构上是独立控制的，并且使用流变仪系统测量每个样品上的水的滑移长度。滑移长度随间距呈线性增加，但在气体分数高于90%时急剧增加，后一种趋势在柱体上比在格栅上更明显。然而，一旦表面设计用于非常大的滑移（>20微米），在常规实践中就无法进一步增加，因为弯月面失去了稳定性。通过开发近乎完美的样品，将从去湿（卡西）状态到湿润（温泽尔）状态的转变延迟到接近理论极限，我们实现了高达185微米的巨大滑移长度。
