稳定超疏水性表面的理论进展

自然界中很多动植物都具有稳定的超疏水性, 它们既拥有高接触角, 又拥有低滚动角, 且能长期稳定存在.通过对它们的研究, 发现表面的润湿性与表面的化学成分、表面的几何形貌有关, 并且表面几何结构的影响更为显著, 甚至可以实现由亲水性表面向超疏水转变. 虽然目前在这个领域已经有大量的实验验证了表面粗糙结构的重要作用, 但是对于表面微纳米结构对表面疏水性机理的理论研究还并不完善. 本文详细介绍了超疏水表面的基本理论及其适用性、 接触角滞后现象, 分别从经典理论和能量的观点探讨了润湿状态转化发生的条件, 重点介绍了通过仿生理念对表面几何形貌的优化设计, 包括单尺度和多尺度表面结构对于设计稳定超疏水表面的作用. 最后, 对超疏水理论的不足和未来发展进行了展望. 关键词： 超疏水 仿生 接触角 滞后

Theoretical progress in designs of stable superhydrophobic surfaces

Controlling the wettability of solid surfaces is an important issue that has aroused the increasing interest from both fundamental and practical perspective by tailoring surface morphology and surface chemical compositions. The underlying theories for interpreting wetting phenomena still mainly focus on the Young's equation, the Wenzel equation, and the Cassie-Baxter equation, despite the fact that the wetting phenomena have been studied over the past decades. While there are a lot of experimental studies on wettability of surface roughness, there is still a lack of a thorough analysis of the contributions of micro and nano-scale roughness to wettability behavior despite interesting features these surfaces have. In this article, the basic theories and their applicabilities are addressed in detail, and the mutual transition between Wenzel state and Cassie-Baxter state is described from different viewpoints in general, and from single-scale and dual-scale point of view in particular. The design concept of geometrical model with stable superhydrophobicity is also described, which is based on the typical theories about wettability. Finally, some promising breakthroughs in the theoretical progress are proposed.
Keywords： superhydrophobic biomimetic contact angle hysteresis