Lower critical solution temperature in polyelectrolyte complex coacervates

Measurements on a common linear oppositely-charged polyelectrolyte complex system, potassium-poly(styrene sulfonate) and poly(diallyl dimethyl ammonium bromide), shows liquid-liquid phase separation upon heating, or lower critical solution temperature behavior. The experimental accessibility of the critical temperature occurs for a narrow range of monovalent salt concentration (Cs) with coexistence curves narrowing with increasing Cs that reduces the polymer concentration (Cp) in the polymer-rich phase. We will describe a qualitative comparison of this phase behavior to available mean field models.