气泡-超疏水表面相互作用纳米力学特性及其机理

Superhydrophobic surfaces have exhibited great potential in underwater drag reduction in marine engineering, because they are capable of adsorbing bubbles and forming gas layers in aqueous environment, which can profoundly change the interfacial properties and hydrodynamic boundary conditions. The interactions between bubbles and superhydrophobic surfaces are critical in the bubble adsorption processes. In this project, the nanomechanical characteristics and physical mechanisms of interactions between air bubbles and superhydrophobic surfaces will be intensively studied. Firstly, bubble probe atomic force microscopy (AFM) technique incorporated with Stokes-Reynolds-Young-Laplace (SRYL) theoretical modeling calculation will be applied to precisely quantify the interactions between air bubbles and hydrophobic/superhydrophobic surfaces under different conditions, in order to explicate the effects of ion specificity in aqueous solutions and the geometrical amplification of surface forces mediated by micro/nano structures. Secondly, sum frequency generation vibrational spectroscopy (SFG-VS) and molecular dynamics (MD) simulation will be utilized to microscopically characterize the network of water molecules and the adsorption of hydrated ions at various gas-water and solid-water interfaces, aiming to reveal the universal rules governing the hydrophobic interfaces’ properties and structures. Finally, the results of the interfacial characterization and nanomechanical quantification will be coupled correspondingly with the purpose of elucidating the physical mechanisms of the bubble-superhydrophobic surface interactions. This work will make significant contribution to the basic understanding of the formation and stabilization mechanism of gas layers on submerged superhydrophobic surfaces, and more importantly, to provide powerful theoretical guidance for realizing and optimizing the underwater drag reduction in marine engineering.

水中的超疏水表面能够吸附气泡并形成气膜，显著地改变界面性质和流体边界条件，因此在海洋工程中水流减阻等方面具有巨大的应用潜力。在气泡吸附和气膜形成的过程中，气泡与超疏水表面之间的相互作用至关重要，决定了气泡的吸附速率和结合强度。本项目通过气泡探针原子力显微镜技术与理论模拟计算相结合的方法，精确量化不同条件下气泡-疏水/超疏水表面相互作用及疏水力等表面力的纳米力学特性，以明确水溶液离子特异性效应和微纳结构表面力几何放大效应的影响机制；通过和频振动光谱技术和分子动力学模拟微观表征气-液和固-液界面水分子的网络结构和水化离子的吸附行为，以揭示支配疏水界面理化性质和组织结构的普适规律；将界面微观表征与纳米力学量化两方面结果对应耦合，建立其映射关系，最终从本质上阐明气泡-超疏水表面相互作用机理。本项目将有助于理解超疏水表面气膜的形成及稳定机制，为实现和优化水下流体减阻等功能提供有力的理论指导。

凭借其低表面自由能与微纳层级结构之间的协同效应，超疏水表面在与水接触时能够形成独特的气-液-固三相复合界面，从而表现出优异的超浸润性（水滴接触角＞150°，水滴滚动角＜10°），在水下流体减阻、水下气体操控、防冰防雾防霜等诸多领域具有巨大的应用潜能和广阔的发展前景。对于复合界面的形成与稳定，由疏水力等表界面相互作用驱动下的气泡吸附与气膜形成等过程则发挥着至关重要的作用。本项目主要利用气泡探针原子力显微镜纳米力学测试技术，结合SRYL理论模拟拟合计算分析，实现了不同条件下气泡与疏水/超疏水表面之间疏水力的精确量化，阐释了水溶液离子特异性效应和微纳结构表面力放大效应的影响机制；通过GROMACS分子动力学模拟计算与数据分析，从分子水平上实现了对不同液-固界面处水分子网络结构的的可视化描述，明确了表面极性基团种类与含量对界面水分子氢键网络的扰乱效果，揭示了支配疏水界面本征理化性质普适规律；建立了界面微观表征分析与纳米力学量化分析两方面结果之间的映射关系，完善了疏水力的物理机理模型，加深了对气泡-疏水/超疏水表面相互作用机理的理解；基于气-液-固胶体系统表界面相互作用机理的研究结果，设计并制备了多种超浸润表面材料，如超疏水防除冰涂层、超亲水防霜雾涂层、动态表面防污涂层等。综上，本项目深入研究了气泡-疏水/超疏水表面相互作用的纳米力学特性及其物理机理，有助于理解超疏水表面气泡吸附与气膜形成过程及其调控机制，为研发新型超浸润表面材料并实现其功能特性提供了可靠的理论指导。