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

Selenium-containing polymers with fascinating functionalities such as stimuli-responsive property, enzyme mimics, antioxidant activity, promotion of immune-cell activity, anticancer activity, and controlled delivery property, are highly desired, but rarely developed due to their underexplored synthetic methods. Herein, through careful design of monomeric structures and polymerization conditions, we report a series of catalyst-free multicomponent polymerizations (MCPs) of elemental selenium with aliphatic/aromatic diamines and diisocyanides that directly converted selenium to polyselenoureas with long-term stability, good solubility, well-characterized structures, and unique functionalities. The MCPs enjoyed broad 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 could be used for the extraction of Au3+ from mixed-metal ion solutions under practical conditions with high selectivity, sensitivity (< 1 μg/L), efficiency (> 99.99%), and capacity (up to 665.60 mgAu3+/g) within 1 min. Further, the elemental gold was recoverable after the pyrolysis of the polymer complexes. © CCS Chemistry 2020.