National Institute for Advanced Industrial Science and Technology (AIST) , 2266-98 Anagahora, Shimo-Shidami, Moriyama-ku Nagoya, Aichi 463-8560, Japan.
Langmuir. 2013 Oct 8;29(40):12472-82. doi: 10.1021/la402714s. Epub 2013 Sep 24.
From a viewpoint of reducing the burden on the environment and human health, an alternative method for preparing liquid-repellent surfaces without relying on the long perfluorocarbons (C((X-1)/2)F(X), X ≥ 17) has been strongly demanded lately. In this study, we have successfully demonstrated that dynamic dewettability toward various probe liquids (polar and nonpolar liquids with high or low surface tension) can be tuned by not only controlling surface chemistries (surface energies) but also the physical (solid-like or liquid-like) nature of the surface. We prepared smooth and transparent organic-inorganic hybrid films exhibiting unusual dynamic dewetting behavior toward various probe liquids using a simple sol-gel reaction based on the co-hydrolysis and co-condensation of a mixture including a range of perfluoroalkylsilanes (FASX, C((X-1)/2)F(X)CH2CH2Si(OR)3, where X = 3, 9, 13, and 17) and tetramethoxysilane (Si(OCH3)4, TMOS). Dynamic contact angle (CA) and substrate tilt angle (TA) measurements confirmed that our FASX-hybrid films exhibited excellent dynamic dewetting properties and were mostly independent of the length of perfluoroalkyl (Rf) groups. For example, 10 μL droplets of ultralow surface tension liquids (e.g., diethyl ether (γ = 16.26 dyn/cm) and n-pentane (γ = 15.51 dyn/cm)) could move easily on our FAS9-, FAS13-, and FAS17-hybrid film surfaces at low substrate TAs (<4°) without pinning. This is comparable or superior to the best perfluorinated textured and flat surfaces reported so far. This exceptional dynamic dewetting behavior appeared only when TMOS molecules were added to the precursor solutions; we assume this is due to co-condensed TMOS-derived silica species working as spacers between the neighboring Rf chains, enabling them to rotate freely and in doing so provide a surface with liquid-like properties. This led to the distinguished dynamic dewettability of our hybrid films, regardless of the small static CAs. Our FASX-hybrid films also displayed excellent chemical and physical durability against thermal stress (~250 °C), high-temperature (150 °C) oil vapor, and various other media (perfluoro liquid, boiling water, and weak acid) without degrading their dynamic dewettability. Such exceptional durability has been rarely seen on conventional perfluorinated surfaces reported so far.
从减少对环境和人体健康的负担的角度来看，最近强烈需要开发一种替代方法来制备不依赖长全氟碳化合物（C((X-1)/2)F(X)，X≥17）的疏液表面。在这项研究中，我们成功地证明，通过控制表面化学（表面能）和表面的物理性质（固态或液态），不仅可以调节对各种探针液体（具有高或低表面张力的极性和非极性液体）的动态润湿性。我们使用简单的溶胶-凝胶反应，基于包括一系列全氟烷基硅烷（FASX，C((X-1)/2)F(X)CH2CH2Si(OR)3，其中 X=3、9、13 和 17）和四甲氧基硅烷（TMOS）的混合物的共水解和共缩合，制备了具有不同动态去湿行为的光滑透明的有机-无机杂化薄膜。动态接触角（CA）和基底倾斜角（TA）测量证实，我们的 FASX 杂化膜表现出优异的动态去湿性能，并且与全氟烷基（Rf）基团的长度基本无关。例如，超低表面张力液体（例如二乙醚（γ=16.26 dyn/cm）和正戊烷（γ=15.51 dyn/cm））的 10 μL 液滴可以在低基底 TA（<4°）下在我们的 FAS9、FAS13 和 FAS17 杂化膜表面上轻松移动而不会被固定。这与迄今为止报道的最好的全氟化纹理和平坦表面相当或更好。这种异常的动态去湿行为仅在将 TMOS 分子添加到前体溶液中时才出现；我们假设这是由于共缩合的 TMOS 衍生的硅物种在相邻的 Rf 链之间作为间隔物起作用，从而使它们能够自由旋转，并由此提供具有液态特性的表面。这导致了我们的杂化膜具有独特的动态润湿性，而与静态 CA 无关。我们的 FASX 杂化膜还表现出优异的耐化学和物理稳定性，可耐受热应力（~250°C）、高温（150°C）油蒸气和各种其他介质（全氟液体、沸水和弱酸），而不会降低其动态润湿性。迄今为止，在报道的传统全氟表面上很少见到这种特殊的耐久性。
