Probing the ion binding capabilities of synthetic polyzwitterions

Zwitterionic polymers have shown great promise for a wide range of applications, including ion-separation membranes in water purification devices. Despite significant advances in the characterization of polyzwitterions in different hydrated environments, the mechanism by which local zwitterionic structure and polymer brush architecture affects selective ion capture has yet to be established. In our work, we developed a tunable polymer platform through which we introduce systematic changes to the chemistry of the side chain and directly examine their impact on the polyzwitterion interactions with different ionic species as well as the chain architecture in solution. Specifically, the solution behavior and selective ion-binding capabilities of cysteine-based polyzwitterions are investigated using a combination of dynamic light scattering, turbidity measurements, and ion-coupled plasma mass spectrometry. A deeper understanding of the interplay between chain dimensions, specific ion interactions and zwitterion identity will allow better control of the binding affinity for different ionic species, opening the door to more efficient design of ion-separation membranes.