Article Thicker lubricant layer enhances the droplet mobility on lubricant-infused smooth surfaces

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) ORCID (Global Networking Division/International Center for Young Scientists, National Institute for Materials Science) ; Ryota Tamate(玉手 亮多) SAMURAI ORCID (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) SAMURAI ORCID (Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science)

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Citation
Ryo Sakai(酒井 遼), Takashi Hiroi(廣井 卓思), Ryota Tamate(玉手 亮多), Timothée Mouterde, Mizuki Tenjimbayashi (天神林 瑞樹). Thicker lubricant layer enhances the droplet mobility on lubricant-infused smooth surfaces. APPLIED PHYSICS LETTERS. 2025, 126 (23), 231602. https://doi.org/10.48505/nims.5531

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(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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  • In Copyright
    This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Ryo Sakai, Takashi Hiroi, Ryota Tamate, Timothée Mouterde, Mizuki Tenjimbayashi; Thicker lubricant layer enhances the droplet mobility on lubricant-infused smooth surfaces. Appl. Phys. Lett. 9 June 2025; 126 (23): 231602 and may be found at https://doi.org/10.1063/5.0274510.

Keyword: liquid slippery surface, droplet friction, Landau–Levich–Derjaguin law

Date published: 2025-06-09

Publisher: AIP Publishing

Journal:

  • APPLIED PHYSICS LETTERS (ISSN: 10773118) vol. 126 issue. 23 231602

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

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