Polystyrenesulfonate Threaded in MIL-101Cr(III): A Cationic Polyelectrolyte Synthesized Directly into a Metal–Organic Framework

Incorporation of an ion-exchange polymer in a metal–organic framework (MOF) is an attractive strategy to achieve fast ion exchange by increasing surface area and porosity of the material. Synthesis of a cationic polyelectrolyte in a MOF is reported here for the first time. Sodium poly(4-styrenesulfonate) threaded in MIL-101 (NaPSS∼MIL-101) is synthesized directly with polymerization in situ of the MOF. NaPSS∼MIL-101 exhibits superior exchange kinetics, high selectivity with co-ion rejection, reversibility, and durability. The polyelectrolyte threaded in MOF has a larger specific volume compared to its bulk state and possesses advantageous properties. The fixed charges of the polyelectrolyte are exposed for full interaction with solvated ions and solvent, without the need of swelling or restructuring the porous framework.