Erbil H Yildirim
Chemical Engineering Department, Gebze Technical University, Gebze 41400, Kocaeli, Turkey.
Langmuir. 2020 Mar 17;36(10):2493-2509. doi: 10.1021/acs.langmuir.9b03908. Epub 2020 Feb 27.
Synthetic superhydrophobic (SH) surfaces were developed after 1990s, and the number of publications in this field is around 13 500 at present. However, the industrial production of SH coatings is very unsatisfying after the intensive research activity in the last two decades. The main reason is the loss of the water repellence properties when SH surfaces are exposed to outdoor conditions due to their weak mechanical properties and contamination from the medium which removes the initial SH properties. In this Feature Article, we focus on the scientific and technical reasons which prevent the application of the SH surfaces in our daily lives by highlighting some well-known but mostly overlooked problems in this area. (The synthesis methods of SH surfaces are not the subject of this article since they were reviewed previously in very good articles.) The basic contact angle science and the issue of the cancellation of the Wenzel and Cassie-Baxter equations are reviewed in the first part. The issues of the expensive and small-scale SH surface preparation problems, the difficulties in obtaining a transparent SH surface, the troubles arising from the water vapor condensation on an SH surface, the lack of robustness and abrasion resistance of most of the SH surfaces, the drawbacks of the fabricated self-healing SH surfaces, the short useful service life of self-cleaning SH surfaces due to surface contamination, and the ineffective anti-icing SH coatings are reviewed in the following text. Some important problems affecting the unsuccessful industrial applications of the SH surfaces are discussed critically in the Conclusions and Outlook section. Finally, some proposals are presented for future directions on the synthesis and applications of SH surfaces.
合成超疏水（SH）表面是在20世纪90年代后开发的，目前该领域的出版物数量约为13500篇。然而，在过去二十年的密集研究活动之后，SH涂层的工业生产却非常不尽人意。主要原因是SH表面暴露在户外条件下时，由于其机械性能较弱以及来自介质的污染会消除初始的SH性能，从而导致疏水性丧失。在这篇专题文章中，我们通过强调该领域一些广为人知但大多被忽视的问题，重点关注阻碍SH表面在我们日常生活中应用的科学和技术原因。（SH表面的合成方法不是本文的主题，因为之前已有非常优秀的文章对其进行了综述。）第一部分回顾了基本的接触角科学以及Wenzel方程和Cassie - Baxter方程失效的问题。接下来将探讨SH表面制备成本高且规模小的问题、获得透明SH表面的困难、SH表面上水蒸气凝结产生的问题、大多数SH表面缺乏坚固性和耐磨性、制备的自修复SH表面的缺点、自清洁SH表面因表面污染而使用寿命短以及无效的防冰SH涂层等问题。在“结论与展望”部分将批判性地讨论影响SH表面工业应用不成功的一些重要问题。最后，针对SH表面的合成和应用的未来方向提出了一些建议。
