离子对具有多环芳香结构的碳基表面动态润湿行为的影响机制研究

Ploycyclic aromatic carbon-based surfaces (PACS) omnipresent in soil, air pollutant and carbon-based nanomaterials, and their wetting behavior significantly affects the water-holding capacity of soil, air pollution control, desalination of sea water and oil/separation process. Due to the attraction force between the PACS and ions, the widespread ions tend to accumulate at the PACS, thus changes the wetting behavior of the PACS. In this case, researchers have make it clear on the static wetting of the PACS, including that the water layer that only exists on superhydrophilic surface was also can be observed on a hydrophobic carbon-base surface under the interaction of ions. In fact, liquid is not only stand still on the surface in many physics, chemistry, and biology process, but also have many dynamic behavior, such as slip, diffusion and convection. Thus, it may be more important to investigate the dynamic wetting behavior of these surfaces. In this project, we want to in-situ study the dynamic wetting behavior of PACS at micro-/nanoscale with the combination of synchrotron radiation x-ray phase contrast imaging technique and AFM. The dynamic wetting process and the interaction between droplets and the PACS were recorded and studied on a series of materials with typical PACS, such as graphite, graphene and carbon nanotube. Then the conclusion on the influence of ions on the dynamic wetting behavior of the PACS was made by comparing the influence at molecular, nano-, micro-, and macro- scale. Finally, the underlying mechanism was unveiled. This project is believed to provide strong experiment evidence for better understanding the wetting behavior of carbon-based surfaces and explore potential applications in the field of industry, agriculture and environment for them.

具有多环芳香结构的碳基表面广泛存在于土壤、大气污染物和碳纳米材料中，其表面润湿行为直接影响土壤保水能力、大气污染防治、海水淡化和油水分离效果。离子广泛存在，而且与芳香环间有较强的相互作用，因此容易在其表面聚集，改变其润湿行为。在这方面，人们已经在静态润湿现象方面取得进展，包括在疏水的碳基表面看到只在超亲水表面才存在的分子水层。事实上，很多物理、化学、生物过程中液体不是静态停留在表面，而是存在滑移、对流和扩散等动态过程。所以，研究这些表面上的动态润湿过程可能更为重要。本项目拟将同步辐射相衬成像技术与AFM技术相结合，以石墨/石墨烯和碳纳米管等典型多环芳香碳基表面为研究对象，研究离子对其动态润湿过程以及液滴/表面间相互作用的影响；并结合其分子/宏观尺度的润湿行为，分析离子对其动态润湿行为的影响规律，建立离子对碳基表面动态润湿行为的影响机制，为碳基表面在农业、工业和环境等领域的发展提供帮助。

具有多环芳香结构的碳基表面广泛存在于土壤、大气污染物和碳纳米材料中，其表面润湿行为直接影响土壤保水能力、大气污染防治、海水淡化和油水分离效果。研究这些表面上的动态润湿过程非常重要。本项目以具有多环芳香结构的石墨、石墨烯、碳纳米管和聚合物为研究对象，利用AFM原位图像和力曲线、接触角测定仪、光学显微镜、扫描电子显微镜等多种实验手段并结合分子动力学模拟方法，在宏观和微观水平上研究了离子对碳基表面的前进接触角和后退接触角以及接触角迟滞、不同湿度下碳基表面的润湿/去润湿行为以及毛细液桥断裂行为的影响，并发展了一种抑制咖啡环效应的新方法。该方法无须改变溶液的性质，也无须精确调控蒸发时液滴中的流场，仅需要添加少量的盐即可，同时还能显著增强沉积层与基底之间的结合力，简单高效地实现了对咖啡环效应的精确控制，为规模化制备高质量的均匀沉积功能化图案提供了一个全新的途径。理论模拟结果表明，离子-π作用对改变碳基表面的动态润湿行为有着非常重要的贡献。本项目中采用的研究手段和取得的结果为进一步研究碳基表面的动态润湿行为提供了理论指导和实验支持。