Reaction-tuned segregation kinetics in binary fluids: Mesoscale insights.

Abstract

We use three-dimensional dissipative particle dynamics to study binary fluids undergoing the reversible reaction A⇌B concurrent with phase separation. The interplay between reaction-induced mixing and interfacial segregation drives the system into nonequilibrium steady states with finite domains. Symmetric reaction rates (k^{f}=k^{b}) lead to a steady domain size R(t), while asymmetric rates induce a crossover from bicontinuous networks to droplet morphologies and then saturation in the asymptotic limit. We characterize these domains using correlation functions and growth laws, R(t)∼t^{θ}, where θ≃1 and 2/3 indicate hydrodynamic growth. Growth saturates at a domain size R_{s}∼k^{-α} with α≃1/3, consistent with scaling predictions and prior studies of reaction-controlled coarsening. Thus, the chemical reaction acts as a competing relaxation channel that gradually shifts the system off criticality, regulates coarsening pathways, and ultimately arrests coarsening.