极端疏水研究

Extreme hydrophobicity is a new concept proposed in this project. It is composed of two features. The first is the contact angle is about 180 degree, and the second is the wetting state is monostable. Specifically, the latter part means after the system is transformed into Wenzel wetting state under perturbation, it can recover a Cassie state without any energy input from environment. Before this project, this monostable Cassie wetting state is thought to be nonexistent. Thus, extreme hydrophobicity is superior to the superhydrophobicity which has attracted lots of attention during the past years. It has the potential to become one of the ideal property for micro- and nano-hydrophobic materials, and is of broad significance for military and civil applications. Preliminary research of the project team shows that such a extreme hydrophobicity state exists on sub-micrometer scale. Recently, we found that the monostable state exists, and developed an original technology which can fabricate nanopillars with characteristic length of 10 nm and certain length-to-radius ratio. These breakthrough provide key theoretical and experimental research basis for this project. The research of this project focuses on the following three parts. 1) The systematic theoretical and experimental study on the mechanisms of extreme hydrophobicity. 2) The fabrication and optimal design of extreme hydrophobic surfaces. 3) The applications of extreme hydrophobic surfaces in related fields such as condensation and heat exchange. With such research focuses, this project is aiming at obtaining pioneering research outcome and technological invention.

极端疏水是本项目提出的一个全新科学概念，有两个主要特征：表观接触角趋近180度，且润湿状态为单稳态（即受到扰动转换成Wenzel湿润状态后，不借助于外界能量输入能够自发恢复到Cassie润湿状态），而之前人们长期认为单稳Cassie润湿状态不存在。因此，极端疏水性超越了广受关注的超疏水性，可望成为微纳米疏水材料研究所追求的理想目标之一，具有广泛和重要的军、民应用潜力。本项目组前期的研究发现这种极端接触角存在于亚微米量级，最近则发现单稳态是存在的，且研发出了可小至10余纳米、具有一定高径比的纳米柱子的原创技术。这些突破，为本项目奠定了关键性的理论、材料制备和实验研究基础。本项目研究内容分为三个方面：（1）极端疏水性机理的理论与实验系统性研究；（2）极端疏水性表面的制备和优化设计；（3）极端疏水性表面在冷凝、换热等相关领域的若干具体应用和产品研发。预期取得多项开拓性的基础研究和技术发明成果。

极端疏水是本项目提出的一个全新科学概念，有两个主要特征：表观接触角趋近180度，且润湿状态为单稳态，而之前人们长期认为单稳Cassie润湿状态不存在。极端疏水性超越了广受关注的超疏水性，可望成为微纳米疏水材料研究所追求的理想目标之一，具有广泛和重要的军、民应用潜力。.本项目取得了多项开拓性的基础研究和技术发明成果：（1）极端疏水性机理的理论与实验系统性研究：首次实现了单稳超疏水状态（液滴润湿状态自发从Wenzel态到Cassie-Baxter态），并揭示了机制，建立了判断准则（2017，PNAS）。（2）极端疏水性表面的制备和优化设计：利用硬质骨架和超疏水浆料结合的方法，制备出了超级耐磨、且具有超疏水、超疏油、可用于柔性基底的超疏水涂层（2020，Advanced Functional Materials）；实现了具有多种几何形貌的金属微纳米结构阵列的研制，拓宽了微纳制造的工艺（2019，Physical Review Letters）。（3）极端疏水性表面在冷凝、换热等相关领域的若干具体应用和产品研发：在单稳态极端疏水表面上发展出了“深度自清洁”的概念，利用液滴润湿状态的转换，实现对微结构内部污染物的清除（2019，ACS AMI）；利用栅格状微结构，调控冷凝液滴的生长，实现了20微米量级、且可以在冷凝过程中全部脱离基底的极端疏水微结构表面（2022，在投）。不仅如此，在极端疏水表面复杂液滴图案的生成、防颗粒脱落性能更佳的防冰涂层的制备、以及利用滴状冷凝液滴弹跳设计制备实现高效冷凝散热装置等方面，本项目超额完成了项目目标。.项目研究成果在Proc. Natl. Acad. Sci.、Physical Review Letters、Advanced Functional Materials、International Journal of Heat and Mass Transfer、ACS Appl. Mater. Interf.等重要期刊和会议发表SCI论文46篇。申请发明专利10项。项目组成员在国际会议上做邀请报告7次，组织会议和研讨会1次，培养研究生21人，并且形成了一支在国际上相关领域具有一定影响的合作紧密、多学科交叉的研究队伍，为本方向的继续深入研究奠定了基础。