Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Orsay, 91405, France.
Department of Applied Physics, Aalto University, Espoo, 02150, Finland.
Nat Commun. 2023 Feb 28;14(1):1125. doi: 10.1038/s41467-023-36763-y.
Foams are unstable jammed materials. They evolve over timescales comparable to their "time of use", which makes the study of their destabilisation mechanisms crucial for applications. In practice, many foams are made from viscoelastic fluids, which are observed to prolong their lifetimes. Despite their importance, we lack understanding of the coarsening mechanism in such systems. We probe the effect of continuous phase viscoelasticity on foam coarsening with foamed emulsions. We show that bubble size evolution is strongly slowed down and foam structure hugely impacted. The main mechanisms responsible are the absence of continuous phase redistribution and a non-trivial link between foam structure and mechanical properties. These combine to give spatially heterogeneous coarsening. Beyond their importance in the design of foamy materials, the results give a macroscopic vision of phase separation in a viscoelastic medium.
泡沫是不稳定的被堵塞的材料。它们随时间演变，时间尺度与它们的“使用时间”相当，这使得研究它们的失稳机制对于应用至关重要。在实践中，许多泡沫是由粘弹性流体制成的，观察到它们会延长其寿命。尽管它们很重要，但我们对这种系统中的粗化机制缺乏了解。我们用泡沫乳液探测连续相粘弹性对泡沫粗化的影响。我们表明，气泡尺寸的演化大大减慢，泡沫结构受到很大影响。主要的机制是连续相再分配的缺失以及泡沫结构和力学性能之间的重要联系。这些结合起来导致了空间不均匀的粗化。除了在泡沫材料设计中的重要性之外，这些结果还从宏观角度展示了粘弹性介质中的相分离。
