Ambre Bouillant - Nucleation and condensation on soft gels

Описание: Condensation of vapor on cool surfaces occurs when ambient humidity exceeds the saturation threshold—a well-known process responsible for dew formation. While this phenomenon has been extensively studied on rigid (and inevitably rough) solids as well as on liquid interfaces, far less is understood when the substrate lies somewhere in between: soft, elastic, and smooth at the nanoscale. Such mechanically hybrid materials are common in both natural environments and engineered systems, yet their role in condensation remains largely unexplored.

In this talk, I will explore how the substrate rheological properties, in particular its elasticity, alter the fundamental process of condensation. Using PDMS gels with tunable stiffness, ranging from solid-like to nearly liquid-like behavior, we study how water vapor condenses on compliant substrates. Surprisingly, despite the nanometric scale of the initial droplets, where one might expect elasticity to be negligible, we observe that the nucleation density is highly sensitive to the substrate's rheology.

I will then discuss the interplay between condensation and substrate mechanics. Notably, we observe a suppression of secondary nucleation events, sub-diffusive droplet growth, and the emergence of persistent, ordered honeycomb patterns resulting from elastocapillary interactions between neighboring droplets. These findings point to a non-trivial coupling between surface mechanics and capillarity, raising new questions at the crossroads of rheology, soft matter physics, phase transitions, and interfacial phenomena.