Two papers accepted in Soft Matter

This week, Soft Matter accepted two of our manuscripts for publication! Both papers investigate how an elastic environment affects the dynamics of many droplets. In particular, they reveal details about elastic ripening, which is the coarsening process driving droplets toward soft regions. While both papers confirm the process of elastic ripening, the details differ significantly:

In the first paper, Estefania Vidal studies our theoretical model of elastic ripening using numerical simulations over a wide parameter regime as well as a coarse-grained model. This simpler model still captures all the relevant details and it allowed us to identify where elastic ripening starts and how fast it progresses. In particular, we derive scaling laws to quickly assess how relevant elastic ripening is in a given experimental situation. Moreover, the coarse-grained model can predict the dynamics in more complex elasticity profiles and it will serve as a starting point for future extensions.

In the second paper, we again teamed up with Eric Dufresne's lab at ETH Zürich to study a more complex situation of elastic ripening where two different silicone gels are brought in contact. By varying experimental conditions, they observed situations in which small droplets grow at the expense of larger droplets (the converse of Ostwald ripening) and situations where the droplet material is transported against its concentration gradient in the dilute phase. By extending our theory of elastic ripening to situations where the saturation concentration can vary in space, we were able to show that both situations reflect elastic ripening.

Taken together, both studies paint a more complete picture of elastic ripening: the extra pressure from the surrounding onto droplets drives material transport from regions of high pressure to low pressure, comparable to Ostwald ripening. However, these studies just began to scratch the surface of how elastic materials can affect droplets. In the future, it will be exciting to see how more complex elastic behavior, viscous effects, and activity affect the dynamics. If we understand these situations in simple in vitro settings, we will also be able to unveil how the elastic cytoskeleton affects biomolecular condensates in cells.