Langmuir. 2023 Jan 17;39(2):709-716. doi: 10.1021/acs.langmuir.2c03318. Epub 2023 Jan 3.
Pinning of droplets on solids is an omnipresent wetting phenomenon that attracts intense research interest. Unlike in classical wetting, pinning effects in a novel wetting problem where droplets are confined onto the substrates by elastic films have hardly been investigated. Here, following our study in an accompanying paper (part 1) on the static mechanics of nanoscale blisters confined between a two-dimensional elastic sheet and its substrate, we investigate in this part the pinning behaviors of such blisters by using atomic force microscopy. The blisters' lateral retention forces are shown to scale almost linearly with their contact lines and to increase until saturation upon increasing their resting times. Our analysis reveals a mechanism of microdeformation of the substrate at the contact line. The creep of the microdeformation is found to cause the time-dependent pinning, which is evidenced by residual fine ridge structures left by blisters after their spread after long resting times.
液滴在固体上的固定是一种普遍存在的润湿现象，引起了强烈的研究兴趣。与经典润湿不同，在一个新的润湿问题中，弹性膜将液滴限制在基底上，其中的固定效应几乎没有被研究过。在这里，在我们对一篇相关论文（第 1 部分）中关于纳米级气泡在二维弹性片与其基底之间的静态力学的研究之后，我们使用原子力显微镜在这一部分研究了这种气泡的固定行为。结果表明，气泡的横向保持力几乎与其接触线呈线性比例，并在增加休息时间时增加到饱和。我们的分析揭示了接触线处基底微变形的机制。发现微变形的蠕变导致了时变固定，这可以通过长时间休息后气泡扩展后留下的残留细脊结构来证明。
