点击次数：

论文类型：期刊论文

发表时间：2017-04-19

发表刊物：ACS APPLIED MATERIALS & INTERFACES

收录刊物：SCIE、EI、PubMed

卷号：9

期号：15

页面范围：13770-13777

ISSN号：1944-8244

关键字：nanostructured superhydrophobic surface; wetting transition; droplet dynamics; condensing condition; spatial confinement; synergistic coordination

摘要：Nanostructured superhydrophobic surfaces have been actively explored to promote favorable droplet dynamics for a wide range of technological applications. However, the tendency of condensed droplets to form as pinned states greatly limits their applicability in enhancing condensation heat transfer efficiency. Despite recent progresses, the understanding, of physical mechanisms governing the wetting transition of condensed droplets is still lacking. In this work, a nanostructured superhydrophobic surface with tapered nanogaps is fabricated to demonstrate the coordination of surface wetting property, topography, and the condensing condition on the wetting state and dynamic behavior of condensed droplets. Combining the environmental scanning electron microscopy and optical visualization methods, we systematically show the morphology of nucleated droplets in nanostructures and the droplet dynamic evolution throughout the growth stages, which provides the direct evidence of condensing condition-induced droplet wetting transition. When the surface subcooling is smaller than 0.3 K, the droplets formed as the Cassie-Baxter state, followed by coalescence-induced droplet jumping. With the increase of surface subcooling up to 0.6 K, however, droplet formation occurs randomly inside nanogaps, resulting in the loss of superhydrophobicity. These new observations along with the new insights about the coordination of surface properties and condensing conditions on droplet wetting transition are useful for guiding the development of novel surfaces for improving droplet removal and phase-change heat transfer.