Identifying liquid-liquid phase boundaries in multicomponent mixtures forming coacervates

Complex coacervation, an associative liquid-liquid phase separation of two charged macromolecules in water and salt, is often used as a method to deliver active ingredients or segregate species into a concentrated phase. Coacervate phase separation results in a macromolecule poor "supernatant" and macromolecule rich "coacervate" phase. Design of a coacervate is complicated by the addition of other species in most solutions; surfactants, salts and other macromolecules move the phase boudaries in unpredictable ways. We are developing ways to rapidly identify phase boundaries using continuous flow milifluidic systems using novel searches of large composition space. The approach also allows many different additives to be studied, elucidating mechanics controlling polyelectrolyte coacervation. We will report on the impact of salt valency and structure. Results will provide feed for development of thermodynamic models and simulation of coacervating systems.