Active Phase Separation and Liquid-Liquid Interfaces

Examples of liquid-liquid phase separation abound throughout material science, biology and everyday life. Immiscible liquid phases are separated by sharp, but deformable interfaces that strongly couple to flows. Biological interfaces are continuously perturbed by active stresses generated locally by energy-dissipating proteins that make cells crawl, change shape, and reorganize their content. Inspired by in-vitro experiments that mix molecular motors and their associated biofilaments with water-soluble phase-separating polymers, we have used continuum models to demonstrate how active stresses provide an alternative method for tuning phase separation and the properties of liquid-liquid interfaces. Activity can both arrest and suppress phase separation, drive giant and anisotropic interfacial fluctuations and system-wide traveling capillary waves in the absence of inertia. Extensile active stresses yield system-spanning filamentary active fluid networks that resemble those formed by organisms such as slime molds or some fungi.

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Note the second seminar given by Cristina Marchetti on Topological defects in active and living matter on 14/05/2025 at 11:30 am at IPGG amphitheater (6 rue Jean Calvin, 75005)