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Contact angle hysteresis with a twist – Stretched droplets on elastic substrates

Year: 2025
Type: article
Abstract: The dynamic wetting behaviour of liquids on deformed surfaces involves a complex interplay of surface tension, substrate elasticity, and droplet adhesion. Nevertheless, conventional methods are often incapable to fully characterise stimuli-responsive surfaces, based on mechano-responsive topography changes under permanent droplet contact. As measuring the contact angle hysteresis is essential for evaluating a surface's wettability, alternative methods for investigating the strain-dependent change of the droplet shape and its contact angles are required. For this purpose, we observed the wetting behaviour of attached droplets during reversible substrate stretching (up to 200%) and relaxation using elastic polydimethylsiloxane with different laser-processed microstructures and chemically functionalised surfaces. The associated droplet shape hysteresis within the range of less than 5° to over 70° shows a significant dependence on the topography and surface chemistry. Pinning and deformation of the three-phase contact line are primarily influenced by permanent air inclusions or complete surface wetting. Comparisons with well-established wetting models and conventional hysteresis measurements confirm that this strain-dependent method provides reliable and reproducible insights into droplet-surface interactions on deformable substrates. These findings enhance the understanding of dynamic wetting processes on elastic materials during reversible mechano-responsive modification and support the development of advanced droplet manipulation strategies for smart surface applications.
DOI: 10.1016/j.apsusc.2025.164911
Authors: Oliver Dubnack, Stephan Gräf, Frank A. Müller
Language: English
Open Access status: hybrid
Estimated APC paid: $3,930
OpenAlex ID: W7092179602
FWCI: 0.41
Cites: 50
Cited by: 2
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