Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 75: Focus Session: Wetting on Adaptive Substrates I (joint session CPP/DY/O)

O 75.1: Invited Talk

Thursday, March 21, 2024, 09:30–10:00, H 0107

Extraordinarily slippery liquid-repellent surfaces using self-assembled monolayers — •Robin Ras — Aalto University, Espoo, Finland

Water-repellent surfaces have the attractive property of staying dry, and find applications in self-cleaning, anti-icing, anti-fogging and much more. Liquid-repellent surfaces, especially smooth solid surfaces with covalently grafted flexible brushes or alkyl monolayers, are the focus of an expanding research area.[1] Surface-tethered flexible species are highly mobile at room temperature, giving solid surfaces a unique liquid-like quality and unprecedented dynamical repellency.

We challenge two common assumptions on liquid-repellency.[2] It is generally assumed that water-repellent surfaces requires hydrophobicity. We demonstrate a hydrophilic surface with the unusual combination of low sliding angle and low contact angle. Surface heterogeneity is generally acknowledged as the major cause of increased contact angle hysteresis and friction of droplets. Here we challenge this long-standing premise for chemical heterogeneity at the molecular length scale.

Furthermore, we demonstrate world’s most slippery surface, by combining self-assembled monolayers and surface structuring. Finally, by a suitable surface texture, we can trap a thin air layer for months, opening new strategies for underwater applications.[3]

[1] Nature Chemistry Reviews (2023) https://doi.org/10.1038/s41570-022-00455-w[2] Nature Chemistry (2023) https://doi.org/10.1038/s41557-023-01346-3 [3] Nature Materials (2023) https://doi.org/10.1038/s41563-023-01670-6

Keywords: hydrophobic surfaces; droplet friction; water repellency; surface modification; superhydrophobic