期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：48
页码：13624-13629
DOI：10.1073/pnas.1607202113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe wetting of solid surfaces by liquids is of great interest in scientific fields ranging from lubrication to the strength of composite materials. These interactions can change dramatically at the nanoscale, impacting on current development of novel devices and materials. We have studied the wetting of individual, size-selected tungsten disulfide nanotubes, both experimentally and theoretically. The results show that wetting forces and free energy can vary by orders of magnitude when capillary action is enhanced in open-ended vs. closed-ended nanotubes, as deduced from the influence of specific nanotube size and geometry in governing the final wetting properties. This work provides a comprehensive view of the molecular-level interactions involved in nanotube wetting. The simple process of a liquid wetting a solid surface is controlled by a plethora of factors--surface texture, liquid droplet size and shape, energetics of both liquid and solid surfaces, as well as their interface. Studying these events at the nanoscale provides insights into the molecular basis of wetting. Nanotube wetting studies are particularly challenging due to their unique shape and small size. Nonetheless, the success of nanotubes, particularly inorganic ones, as fillers in composite materials makes it essential to understand how common liquids wet them. Here, we present a comprehensive wetting study of individual tungsten disulfide nanotubes by water. We reveal the nature of interaction at the inert outer wall and show that remarkably high wetting forces are attained on small, open-ended nanotubes due to capillary aspiration into the hollow core. This study provides a theoretical and experimental paradigm for this intricate problem.
