Nanoscale wettability, crucial for various disciplines in science and engineering, challenges traditional theory, particularly the Young's equation. This study proposes and validates a modified format of the Young's equation under nano‐confinement and, for the first time, the nano‐confined droplet morphological evolution and transition are investigated from thermodynamic theories and molecular dynamics simulation. The morphologies of droplets in nano‐silts, identified as double‐cap, single‐cap, and bridge‐shaped, underscore the critical roles of line tension and nano‐confinement in characterizing wetting behavior. In hydrophobic nano‐slits, droplets transition from the double‐cap to the single‐cap shape at the critical point of = 0.31 and to bridge shape at the critical point of = 0.40. Moreover, the relative width of the neck region in the bridge‐shaped droplets is found to stabilize at ratio of 1.8. Particularly, linear relationships have been established between the droplet contact angle and the parameter , which identify condensation and breakage of droplets within hydrophobic nano‐slits. This model effectively characterizes nanoscale wettability, with precise droplet behavior predictions, which could be beneficial to enhance nano‐fluid dynamics understanding and its applications in science and engineering.

中文翻译：

---

纳米级润湿性表征 — 解释纳米孔中的液滴形态演变


纳米尺度润湿性对科学和工程的各个学科都至关重要，它挑战了传统理论，尤其是杨氏方程。本研究提出并验证了纳米限域下杨氏方程的改进格式，并首次从热力学理论和分子动力学模拟中研究了纳米限域液滴形态的演变和转变。纳米淤泥中液滴的形态被鉴定为双帽、单帽和桥形，强调了线张力和纳米限度在表征润湿行为中的关键作用。在疏水性纳米狭缝中，液滴在临界点 = 0.31 处从双帽转变为单帽形状，在临界点 = 0.40 处转变为桥状。此外，发现桥状液滴中颈部区域的相对宽度稳定在 1.8 的比率。特别是，液滴接触角和参数 之间建立了线性关系，该参数确定了疏水性纳米狭缝内液滴的冷凝和破裂。该模型通过精确的液滴行为预测有效地表征了纳米尺度的润湿性，这可能有助于增强对纳米流体动力学的理解及其在科学和工程中的应用。