Phase separation in active binary mixtures with chemical reaction

Abstract

We study motility-induced phase separation (MIPS) in active AB binary mixtures undergoing the chemical reaction A ⇌ B. Starting from the evolution equations for the density fields ρ_i(,t) describing MIPS, we phenomenologically incorporate the effects of the reaction through the reaction rate Γ into the equations. The steady-state domain morphologies depend on Γ and the relative activity of the species, Δ. For a sufficiently large Γ and Δ ≠ 1, the more active component of the mixture forms a droplet morphology. We characterize the morphology of domains by calculating the equal-time correlation function C(r,t) and the structure factor S(k,t), exhibiting scaling violation. The average domain size, L(t), follows a diffusive growth as L(t) ∼ t^1/3 before reaching the steady state domain size, L_ss. Additionally, L_ss shows the scaling relation L_ss∼ Γ^−1/4, independent of Δ.