Coarsening is a crucial phenomenon in bubbly media through which bubbles grow over time. In the capillary regime, i.e., when the surrounding fluid is a simple liquid, the cube of the bubble radius grows linearly with time. What happens when the simple liquid is replaced by a complex elastoplastic fluid? To answer this question, we perform two experiments with a foamed concentrated emulsion: one investigates the growth law over long durations with an emulsion having a constant yield stress, while in the other the emulsion yield stress continuously increases until coarsening arrests. Our results show that for Bingham capillary numbers (Bi), comparing yield stress to capillary effects, greater than approximately 0.1, plastic stresses slow down coarsening. We extend the growth law to capture this effect by introducing a damping factor dependent on the critical value ${\mathrm{Bi}}^{*}$, which marks the arrest of coarsening; it allows us to describe all our bubble growth data for liquid fractions ranging from 58% to 96%. Furthermore, we explain the evolution of ${\mathrm{Bi}}^{*}$ as a function of the liquid fraction using the effective yield stress of the bubbly emulsion. This work provides insights into the design of stable porous materials by demonstrating how matrix plasticity can be leveraged to control microstructure evolution, with implications for materials requiring optimized mechanical response.

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• Polymer aging
• Foams