Local Segmental Dynamics of Polyelectrolyte in Complex Coacervates
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초록
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Complex coacervates are polymer-rich phase of liquid-liquid phase separation when two oppositely charged polyelectrolytes are mixed in aqueous solutions. Previously, rheological measurements on the complex coacervates have shown that the ionic bonds of polyelectrolytes significantly slow down polymer chain dynamics. However, the local segmental dynamics of polymer chain in the complex coacervates have not studied yet. In this study, the segmental dynamics of complex coacervates are revealed as a function of salt concentration by quasi-elastic neutron scattering. Model polyelectrolytes functionalized with cationic ammonium or guanidinium, and anionic sulfonate groups were synthesized by anionic ring-opening polymerization. As the salt concentration increases, the amount of unpaired segments in ammonium-based coacervates increases, resulting in enhanced segmental relaxation. In contrast, guanidinium-based coacervates show slow segmental dynamics independent on the salt concentration.