CAREER: Diffusive and Convective Gas Dissolution over Super-Hydrophobic Surfaces

超疏水表面最初发现于荷叶上，最近显示出成为下一代多功能材料的巨大潜力。当浸入液体中时，这些表面在表面纹理之间捕获一层气体，从而使许多行业受益于海上运输中的节能，以保护海底结构免受腐蚀和生物污染。然而，有益气体可以溶解在环境液体中，并且可能仅持续有限的时间，这大大限制了超疏水表面的实际应用。该项目旨在通过创新实验了解这种气体溶解过程，并开发新的策略来延长气体的寿命。研究工作与包括五项活动的教育和外联计划很好地结合在一起：本科生主导的原创性研究，高中生的暑期研讨会，K-12学生的桌面实验，当地自主水下航行器制造商的课堂旅行，以及东南部新英格兰地区海洋工业的技术展示。缺乏同时测量质量通量的实验研究，速度场和气体浓度场，这是控制气体从超疏水表面溶解到液体中的三个关键参数。该项目填补了这一空白，并通过结合三种先进的光学技术来测量这三个参数：反射干涉对比显微镜，平面激光诱导荧光抑制和全息粒子图像测速。第一个目的是研究气体在静止液体中的扩散传递。结果将揭示液体中气体浓度的变化，并最终影响质量通量。通过系统地改变纹理参数（高度、波长和气体分数），将建立气体寿命的预测模型。第二个目的是研究层流和湍流中的对流气体传递。通过改变样品的滑移长度，提出了滑移边界上舍伍德数的新的标度模型。第三个目标是通过研究四种被动和主动方法对气体寿命的影响来对抗气体溶解问题：纳米级粗糙度，再入几何形状，通过多孔材料的气体注入，以及过饱和水的气体转移。该项目将是变革性的，并推进我们对新材料复杂边界处的传质、界面稳定性和流动动力学的基本理解。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Superhydrophobic surfaces, initially found on lotus leaves, have recently shown great potential to be the next generation of multi-function materials. These surfaces trap a layer of gas between the surface textures when immersed in liquid, and consequently benefit many industries from saving energy in maritime transport, to protecting undersea structures from corrosion and biofouling. However, the beneficial gas could be dissolved in ambient liquid and may last only for a limited amount of time, significantly limiting the real-world applications of superhydrophobic surfaces. This project aims to understand this gas dissolution process through innovative experiments and develop new strategies to extend the longevity of gas. The research efforts are well integrated with an education and outreach plan including five activities: undergraduate student-lead original research, summer workshop for high-school students, table-top experiments for K-12 students, class trip to a local autonomous underwater vehicle manufacturer, and technology showcase to marine industry in the Southeastern New England area.There is a lack of experimental studies which simultaneously measure mass flux, velocity field and gas concentration field, which are three key parameters that govern the dissolution of gas from the superhydrophobic surfaces to the liquid. This project fills this gap and measures the three parameters by combining three advanced optical technologies: Reflective Interference Contrast Microscopy, Planar Laser-Induced Fluorescence with Inhibition, and Holographic Particle Image Velocimetry. The first objective is to investigate the diffusive gas transfer in stationary liquid. The results will reveal how gas concentration in liquid changes and ultimately affects the mass flux. By systemically varying the texture parameters (height, wavelength, and gas fraction), predictive models of gas longevity will be established. The second objective is to examine the convective gas transfer in laminar and turbulent flows. By varying the slip length of the samples, new scaling models of Sherwood number over slip boundaries will be proposed. The third objective is to combat the gas dissolution issue by studying the impacts of four passive and active methods on gas longevity: nano-scale roughness, re-entrant geometry, gas injection through a porous material, and gas transfer from supersaturated water. This project will be transformative and advance our fundamental understanding of mass transfer, interfacial stability, and flow dynamics at complex boundaries of novel materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.