Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 102: Focus Session: Wetting on Adaptive Substrates III (joint session CPP/DY/O)
O 102.1: Hauptvortrag
Freitag, 22. März 2024, 09:30–10:00, H 0110
Condensation on soft substrates — •Ambre Bouillant1,3, Bruno Andreotti2, and Jacco H. Snoeijer3 — 1Laboratoire MSC, CNRS UMR 7057, Université Paris Cité, FR — 2Laboratoire LPENS, CNRS UMR 8023, Université PSL, FR — 3Physics of Fluids, Twente Unversity, NL
Vapor molecules can nucleate on cool substrates, provided the surrounding humidity is high enough. Dew formation has been investigated on both rigid (and rough!) solids as well as on liquids. However, how substrate elasticity affects the condensation process remains elusive. In this talk, I will present how water condenses on soft, elastic gels that are smooth at the nanometer scale. We prepare PDMS gels whose softness varies between that of a rigid substrate and an un-crosslinked polymeric liquid.
Although elasticity should be marginal at the nanometric scale at which drops form, we report that the nuclei density is highly sensitive to the substrate softness. Throughout this talk, I will delve into the intricate dynamics of condensation and try to explain some of the intriguing characteristics we have observed. Among these are the influence of softness on nucleation; the sub-diffusive growth of droplets; and the absence of secondary nucleation events (unlike what is classically observed in heterogeneous nucleation). Later, when neighboring drops get closer, they attract each other due to interactions mediated by substrate deformations. Drops then gather into clusters that seem reluctant to coalesce. This ultimately results in the formation of a persistent, ordered, honeycomb-patterned liquid film.