Interfacial tension in polyelectrolyte systems exhibiting associative liquid-liquid phase separation

Abstract A continued interest in polyelectrolyte phase diagrams guides the study of interfacial phenomena driven by polyelectrolyte complexation. The liquid-liquid interfaces formed by associative phase separation of oppositely charged synthetic and natural polyelectrolytes provide measurement challenges addressed by force-sensitive methods and deformed droplet retraction. The ultralow interfacial tension, typical of these systems, are sensitive to salt concentration and temperature and display universal features described by mean field theory. Several areas of fundamental development as well as novel applications of charge complexation for interfacial study and examples from membraneless organelles and biomolecular condensates are described.