Anti-polyelectrolyte Zwitterionic Block Copolymers as Adaptable Uranium Harvester in High-Salinity Environments: Catalyst-Free Light-Driven Polymerization and Conformational Dynamics Study

Abstract

Developing polymeric adsorbents for uranium harvesting from high-salinity environments remains a daunting challenge due to the ‘polyelectrolyte effect’-induced conformational collapse compromising the ligand availability. A catalyst-free, visible light-controlled radical polymerization has been presented here for the tailor-made synthesis of zwitterionic block copolymers (BCPs) bearing uranophilic ligands. The novel anti-polyelectrolyte uranium harvesters exhibited significant salinity resistance. The facile and robust photosynthetic strategy offers a significantly high monomer conversion (α > 95%) that facilitates “one-pot” chain extension to develop the BCPs. Metal catalyst residues, as found in conventional controlled radical polymerizations, are avoided and promoted to synthesize fascinating polymeric materials. We also highlight the first study, by integrating computational modeling with QCM-D analysis, on the interplay between polymer conformational dynamics and chemical adsorption behaviors. With zwitterionic polymer segments as conformational regulators, the BCPs exhibit remarkable ‘anti-polyelectrolyte effect’ by maintaining stretched conformations in saline solutions. Improved ligand accessibility and promotion of diffusional mass transfer are achieved, enabling a high adsorption capacity toward uranium with remarkably fast kinetics in spiked natural seawater and salt lake brines.

Graphical Abstract

A catalyst-free, visible light-regulated RAFT polymerization method is established to develop zwitterionic block copolymers bearing uranophilic ligands as new-generation uranium harvesters adaptable in high-salinity environments.

Funding

National Natural Science Foundation of China(21922604)