  Chemically driven fluids can demix to form condensed droplets that exhibit
phase behaviors not observed at equilibrium. In particular, nonequilibrium
interfacial properties can emerge when the chemical reactions are driven
differentially between the interior and exterior of the phase-separated
droplets. Here, we use a minimal model to study changes in the interfacial
tension between coexisting phases away from equilibrium. Simulations of both
droplet nucleation and interface roughness indicate that the nonequilibrium
interfacial tension can either be increased or decreased relative to its
equilibrium value, depending on whether the driven chemical reactions are
accelerated or decelerated within the droplets. Finally, we show that these
observations can be understood using a predictive theory based on an effective
thermodynamic equilibrium.
