Ionic-Group Dependence of Polyelectrolyte Coacervate Phase Behavior
Sojeong Kim, Minhwan Lee, Won Bo Lee, Soo‐Hyung Choi
Abstract
A complex coacervate is the polymer-rich phase resulting from liquid–liquid phase separation induced by two oppositely charged polyelectrolytes in an aqueous solution, which shows the considerable potential of functional materials and the substantial role of biological processes. In this study, the phase behavior of complex coacervates for differently charged moieties is investigated using well-defined polyether-based polyelectrolytes functionalized with ammonium, guanidinium, sulfonate, and carboxylate groups. Turbidity measurement and thermogravimetric analysis provide the stability and phase diagram of the complex coacervates, indicating a significant role of the pair of charged groups. In stark contrast to ammonium-based coacervates, guanidinium-based coacervates show considerable stability upon the addition of salt and enhanced dehydration with increasing salt at low salt concentrations. Together with all-atomistic molecular dynamics simulations, it is demonstrated that the chemical-specific interactions between charged molecules and the role of salts depending on the charged groups play essential roles in controlling the phase behavior of complex coacervates.