State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China.
State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics , Chinese Academy of Sciences , 15 Beisihuanxi Road , Beijing 100190 , China.
Langmuir. 2018 Nov 20;34(46):14096-14101. doi: 10.1021/acs.langmuir.8b03290. Epub 2018 Nov 9.
Surface nanobubbles have been presumed to lead to the experimental observation that liquid boiling often occurs at a much lower supersaturation than expected, yet no qualitative theory exists to explain how they participate in the process. Here, we report through a simple theoretical analysis on how the metastable nanobubbles nucleate the liquid-to-vapor transition by serving as an intermediate phase. The appearance of metastable nanobubbles inhibits the shrink of the bubble nucleus and changes bubble nucleation into a multistep process. We show three possible mechanisms for heterogeneous nucleation starting from metastable surface nanobubbles: nucleation from pinned nanobubbles, nucleation via nanobubble depinning, and nucleation through nanobubble coalescence, each predicting a significant reduction in a nucleation barrier. The occurrence of a specific nucleation pathway of bubble nucleation depends on the detailed geometry of local substrate roughness. These results give insight into how the appearance of surface nanobubbles changes the nucleation mechanisms of liquid boiling.
表面纳米气泡被认为是导致实验观察到液体沸腾经常在远低于预期过饱和度下发生的原因，但目前还没有定性理论来解释它们如何参与这个过程。在这里，我们通过一个简单的理论分析报告了亚稳纳米气泡如何通过充当中间相来引发液-气相变的成核。亚稳纳米气泡的出现抑制了气泡核的收缩，并将气泡成核改变为多步过程。我们展示了从亚稳表面纳米气泡开始的三种可能的异质成核机制：从固定纳米气泡成核、通过纳米气泡去钉核以及通过纳米气泡聚合并核，每种机制都预测成核势垒会显著降低。气泡成核的特定成核途径的发生取决于局部基底粗糙度的详细几何形状。这些结果深入了解了表面纳米气泡的出现如何改变液体沸腾的成核机制。
