Water wettability of floating graphene: Mechanism and Application

固体表面的水润湿性通常通过对固体表面使用不同的材料或通过涂覆表面来改变。然而，过去八年的研究表明，水可以（至少部分地）“看穿”石墨烯等原子厚度的材料层，从而产生所谓的“润湿透明”效应。这一发现为设计多功能器件提供了一个独特的机会，因为它意味着原子厚度的膜的润湿性可以通过选择合适的支撑基底来调节。 如果衬底是液体，则图像变得更加吸引人，因为人们可以容易地改变石墨烯下面的液体，从而提供对润湿性的实时控制，这是一种对于从空气中和液滴微流体装置中收集水分非常有用的能力。该项目的研究目标是利用实验和计算模拟来了解石墨烯在液体基底上润湿透明的机制，并演示表面润湿性的实时控制。 该项目将以多种方式促进从K-12到研究生对研究的兴趣和参与，例如，通过为研究生和本科生提供研究培训，开发新课程，并开展推广活动。 PI将整合实验和计算工作，以实现两个特定目标。首先，液体基板如何影响石墨烯的润湿性将通过研究分子迁移率，电荷掺杂，极化和分散相互作用如何影响润湿透明度来揭示。第二，润湿性调制的范围以及浮动石墨烯的机械鲁棒性将得到增强，并且润湿性的实时操纵将得到证明。 将阐明石墨烯在液体基底上的润湿透明性的性质，并且将构建和利用包括电荷流极化和多体分散的最先进的力场来计算浮动石墨烯的润湿性，并建立润湿透明性的各种类型的相互作用的相对重要性。使用液体作为支撑基底为设计具有实时润湿性控制的设备开辟了一个新的维度，这在水收集、生物医学设备、热交换、微反应器和化学分离中非常理想。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。

The water wettability of a solid surface is usually changed either by using a different material for the solid surface or by coating the surface. However, research over the past eight years has shown that water can (at least partially) “see through” an atomic-thick layer of a material such as graphene, giving rise to so-called “wetting transparency” effect. This finding provides a unique opportunity for designing multi-functional devices since it means that the wettability of an atomic-thick film can be tuned by selecting an appropriate supporting substrate. The picture becomes even more appealing if the substrate is a liquid, since one can readily change the liquid underneath the graphene, thereby providing real-time control of the wettability, a capability that would be very useful for water harvesting of moisture from the air and in droplet microfluidics devices. The research objectives of this project are to use experiments and computational simulations to understand the mechanisms of wetting transparency of graphene on liquid substrates and to demonstrate the real-time control of surface wettability. This project will promote the interest and participation in research from K-12 to graduate students in many ways, e.g., by providing research training to graduate and undergraduate students, developing new courses, and conducting outreach activities. The PIs will integrate experimental and computational efforts to pursue two specific aims. First, how liquid substrates affect the wettability of graphene will be uncovered by investigating how molecular mobility, charge doping, polarization, and dispersion interactions impact the wetting transparency. Second, the range of wettability modulation as well as the mechanical robustness of floating graphene will be enhanced, and the real-time manipulation of the wettability will be demonstrated. The nature of wetting transparency of graphene on liquid substrates will be elucidated, and a state-of-the-art force field, including charge-flow polarization and many-body dispersion, will be constructed and utilized to compute the wettability of floating graphene and to establish the relative importance of various types of interactions for the wetting transparency. Using liquid as the supporting substrate opens a new dimension for designing devices with real-time wettability control, which is highly desirable in water harvesting, biomedical devices, heat exchange, micro reactors and chemical separation.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.