Polyelectrolyte hydrogel capsules as stabilizers for reconfigurable complex emulsions

Responsive complex emulsions are increasingly of interest for use in diagnostics, optics, and chemical sensing due to their tunable chemical and physical properties. A significant limitation of such fluid droplets for long-term applications is their eventual breakdown over time by pathways such as coalescence and Ostwald ripening that lead to variations in droplet size and composition. Elucidating approaches by which to enhance droplet stability while simultaneously maintaining their reconfigurability and responsive character is therefore important. This report explores the behavior of reconfigurable hydrocarbon and fluorocarbon droplets in water that are encapsulated in a polyelectrolyte hydrogel shell. Surfactant-free gelation pathways are investigated to form oil-core calcium alginate capsules, and the effects of the hydrogel capsule structure on droplet stability and reconfigurability in the presence of surfactants are characterized.