Capillary interfacial tension in active phase separation

2021/03/31 by Giordano Fausti, Elsen Tjhung, Michael Cates +1 · 2 citations
Physics and Astronomy · #cond-mat.soft #cond-mat.stat-mech

paper · pdf · doi:10.1103/physrevlett.127.068001

published as Phys. Rev. Lett. 127, 068001 (2021) · as accepted for publication in Phys. Rev. Lett

arxiv created 2021/07/14 · arxiv updated 2021/08/11

Abstract

In passive fluid-fluid phase separation, a single interfacial tension sets both the capillary fluctuations of the interface and the rate of Ostwald ripening. We show that these phenomena are governed by two different tensions in active systems, and compute the capillary tension σ_cw which sets the relaxation rate of interfacial fluctuations in accordance with capillary wave theory. We discover that strong enough activity can cause negative σ_cw. In this regime, depending on the global composition, the system self-organizes, either into a microphase-separated state in which coalescence is highly inhibited, or into an `active foam' state. Our results are obtained for Active Model B+, a minimal continuum model which, although generic, admits significant analytical progress.

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