Soft materials in complex environments: From porous rocks to the gut

Soft materials in complex environments:  From porous rocks to the gut

As a field, we have made tremendous progress in understanding the bulk behavior of soft materials. However, diverse applications rely on how these materials behave in complex environments--where environmental
factors alter material microstructure, the material itself alters the environment, and these coupled dynamics give rise to non-trivial emergent effects. This poses new challenges to our understanding. In this talk, I will describe two examples, in two very different settings, of how we disentangle the interactions between soft materials and their environments. First, I will describe how we visualize single-phase and multi-phase flow within a disordered 3D
porous medium, over length scales ranging from smaller than a pore to that of the entire medium. This enables us to elucidate the physical origin of fluctuations and fluid instabilities in this complex system. Second, I will describe how we combine animal experiments, microscopy, and thermodynamic modeling to probe the mucus hydrogel which lines and protects the gut. We find that polymers in the gut entropically compress this hydrogel; moreover, this behavior can be modulated by gut microbes, revealing an unexpected interplay between polymer content, gut microbiota, and the biological structures that protect us. Ultimately, this research stimulates new findings and questions at the interface of engineering, physics, and biology.gth scales.