Thickness of Nanoscale Poly (Dimethylsiloxane) Layers Determines the Motion of Sliding Water Drops

Abstract: Layers of nanometer thick polydimethylsiloxane (PDMS) are applied as hydrophobic coatings because of their environmentally friendly and chemically inert properties. In applications such as heat exchangers or fog harvesting, low water drop friction on surfaces is required. While the onset of motion (static friction) has been studied, the knowledge of dynamic friction needs to be improved. To minimize drop friction, it is essential to understand which processes lead to energy dissipation and cause dynamic friction? Here, the dynamic friction of drops on PDMS brushes of different thicknesses is measured, covering the whole available velocity regime. The brush thickness L turns out to be a predictor for drop friction. 4–5 nm thick PDMS brush shows the lowest dynamic friction. A certain minimal thickness is necessary to form homogeneous surfaces and reduce the attractive van der Waals interaction between water and the substrate. The increase in dynamic friction above L = 5 nm is also attributed to the increasing viscoelastic dissipation of the capillary ridge formed at the contact line. The height of the ridge is related to the brush thickness. Fluorescence correlation spectroscopy and atomic force measurements support this interpretation. Sum‐frequency generation further indicates a maximum order at the PDMS–water interface at intermediate thickness.

Standort
Deutsche Nationalbibliothek Frankfurt am Main
Umfang
Online-Ressource
Sprache
Englisch

Erschienen in
Thickness of Nanoscale Poly (Dimethylsiloxane) Layers Determines the Motion of Sliding Water Drops ; day:27 ; month:05 ; year:2024 ; extent:13
Advanced materials ; (27.05.2024) (gesamt 13)

Urheber
Zhou, Xiaoteng
Wang, Yongkang
Li, Xiaomei
Sudersan, Pranav
Amann‐Winkel, Katrin
Koynov, Kaloian
Nagata, Yuki
Berger, Rüdiger
Butt, Hans-Jürgen

DOI
10.1002/adma.202311470
URN
urn:nbn:de:101:1-2405271420141.852744753689
Rechteinformation
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Letzte Aktualisierung
14.08.2025, 10:45 MESZ

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