Many important processes—from the manufacturing of integrated circuit boards to an insect’s ability to walk on water—depend on the wetting of liquids on surfaces. Wetting is commonly controlled through material selection, coatings, and/or surface texture. However, wetting is sensitive to environmental conditions. In particular, some hydrophobic fluoropolymer coatings are sensitive to extended water exposure as evidenced by a declining contact angle and increasing contact angle hysteresis. Understanding “degradation” of these coatings is critical to applications that deploy them. The durability of a series of fluoropolymer coatings was tested by measuring the water contact angle before, during, and after extended submersion of coated glass slides in a deionized water bath. Vibration was introduced as a potential method for expediting the effects of long-term water exposure, so similar measurements were taken before, during, and after the same coatings were subject to ultrasonic vibration while covered in deionized water. Both methods caused changes in advancing and receding contact angles, but degradation rates of vibrated coatings were significantly increased. Prolonged soaking caused significant decreases in the contact angle of most of the samples, though most experienced significant recovery of hydrophobicity when heat-treated at 160°C after submersion. Some coatings appeared noticeably more resistant to degradation by one or both methods. FluoroSyl showed no clear change under submersion, while other coatings experienced significant contact angle change. Degradation of vibrated coatings was also inconsistent among coatings and was not simply an acceleration of the degradation resulting from submerging coatings in water. This was apparent as some coatings were affected by one method but not the other. Atomic force microscopy was utilized to characterize the surface roughness of the coatings and revealed differing surface effects for different coatings after submersion and heat treatment. However, the magnitude of this roughness change was insufficient to fully explain the wetting changes. The rate of contact angle degradation was not altered significantly for coatings that were vibrated with acceleration magnitudes between 700 and 7000 g.

中文翻译：

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浸没在水中并超声振动的疏水性含氟聚合物涂料的润湿变形

从集成电路板的制造到昆虫在水上行走的能力，许多重要过程都取决于液体在表面上的润湿性。通常通过材料选择，涂层和/或表面纹理来控制润湿。但是，润湿对环境条件敏感。特别地，某些疏水性含氟聚合物涂料对延长的水暴露敏感，如接触角减小和接触角滞后性增加所证明的。了解这些涂层的“降解”对于部署它们的应用至关重要。一系列含氟聚合物涂料的耐久性通过在涂层玻璃载玻片长时间浸入去离子水浴之前，之中和之后测量水接触角来测试。引入振动是加快长期暴露于水的影响的一种潜在方法，因此在将去离子水中覆盖的相同涂层进行超声波振动之前，期间和之后进行了类似的测量。两种方法都会引起前进和后退接触角的变化，但是振动涂层的降解率显着提高。长时间浸泡会导致大多数样品的接触角显着减小，尽管大多数在浸没后在160°C热处理时疏水性明显恢复。某些涂层似乎通过一种或两种方法均具有更高的抗降解性。FluoroSyl在浸没下没有明显变化，而其他涂层的接触角却发生了明显变化。振动涂层的降解在各涂层之间也是不一致的，不仅仅是由于将涂层浸没在水中而导致的降解加速。这很明显，因为某些涂层受一种方法影响，而不受另一种方法影响。利用原子力显微镜表征了涂层的表面粗糙度，并揭示了浸没和热处理后不同涂层的不同表面效应。但是，这种粗糙度变化的幅度不足以完全解释润湿变化。对于以700到7000 g的加速度幅度振动的涂层，接触角的降解速率没有明显改变。这很明显，因为某些涂层受一种方法影响，而不受另一种方法影响。利用原子力显微镜表征了涂层的表面粗糙度，并揭示了浸没和热处理后不同涂层的不同表面效应。但是，这种粗糙度变化的幅度不足以完全解释润湿变化。对于以700到7000 g的加速度幅度振动的涂层，接触角的降解速率没有明显改变。这很明显，因为某些涂层受一种方法影响，而不受另一种方法影响。利用原子力显微镜表征了涂层的表面粗糙度，并揭示了浸没和热处理后不同涂层的不同表面效应。但是，这种粗糙度变化的幅度不足以完全解释润湿变化。对于以700到7000 g的加速度幅度振动的涂层，接触角的降解速率没有明显改变。