Ryo Sakai(酒井 遼)
(Research Center for Materials Nanoarchitectonics (MANA)/Nanomaterials Field/Frontier Molecules Group, National Institute for Materials Science)
;
Takashi Hiroi(廣井 卓思)
(Global Networking Division/International Center for Young Scientists, National Institute for Materials Science)
;
Ryota Tamate(玉手 亮多)
(Research Center for Macromolecules and Biomaterials/Macromolecules Field/Molecular Design and Function Group, National Institute for Materials Science)
;
Timothée Mouterde
(The university of Tokyo)
;
Mizuki Tenjimbayashi (天神林 瑞樹)
(Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science)
Description:
(abstract)Droplets are highly mobile on lubricant-infused surfaces when droplet−lubricant phases are immiscible and lubricant layer is stable. Recent studies have shown that the high droplet mobility is due to absence of three-phase contact line friction by oleoplaning of the droplets on the lubricant layer. In this state, dynamic friction arises primarily from viscous dissipation in the lubricant around the droplet. Classical Landau–Levich–Derjaguin (LLD) law suggests that the friction force is proportional to the two-thirds power of the capillary number, and the lubricant thickness effect is not included. Here, we discovered that increased lubricant thickness enhances the droplet's mobility on lubricant-infused surfaces. This finding is unexpected, as a thicker lubricant layer would typically increase the potential volume for viscous dissipation. We formed stable lubricant layers of varying thicknesses ranging from tens to hundreds of micrometers on a "nanometrically smooth" base layer to remove the influence of surface texture. The droplet friction force on the different lubricant thickness surfaces is measured using the cantilever method. While all surfaces follow LLD law, the friction force significantly decreases with increasing the lubricant thicknesses. The possible reason is the decrement of the energy dissipation at the lubricant ridge with the thickness. We propose a modified friction model incorporating the thickness dependence with the classical law, offering deeper insight into droplet friction dynamics on the lubricant-infused surfaces. In practical terms, reducing droplet friction enhances transport efficiency, contributing to advancements in fluidic systems and liquid-repellent applications.
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Keyword: liquid slippery surface, droplet friction, Landau–Levich–Derjaguin law
Date published: 2025-06-09
Publisher: AIP Publishing
Journal:
Funding:
Manuscript type: Author's version (Accepted manuscript)
MDR DOI: https://doi.org/10.48505/nims.5531
First published URL: https://doi.org/10.1063/5.0274510
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Updated at: 2025-06-10 12:02:07 +0900
Published on MDR: 2025-06-10 16:20:22 +0900