Functional Polyselenoureas for Selective Gold Recovery Prepared from Catalyst-Free Multicomponent Polymerizations of Elemental Selenium

Selenium-containing polymers with fascinating functionalities are highly desired but are rarely developed due to their underexplored synthetic methods. Herein, through careful design of monomer structures and polymerization conditions, a series of catalyst-free multicomponent polymerizations (MCPs) of elemental selenium with aliphatic/aromatic diamines and diisocyanides were reported to directly convert elemental selenium to polyselenoureas with long-term stability, good solubility, well-characterized structures, and unique functionalities. The MCPs enjoy wide monomer scope and fast conversion in 1 min, delivering 18 polyselenoureas with high molecular weights (Mws up to 94 600 g/mol) in high yields (up to 99%). Furthermore, the polyselenoureas can be used for the extraction of Au3+ from mixed metal ion solutions in practical conditions with high selectivity, sensitivity (< 1 μg/L), efficiency (> 99.99%), and capacity (up to 665.60 mg·Au3+/g) within 1 min, and elemental gold can be further recovered after pyrolysis of the polymer complexes.