Cyclized polyacrylonitrile amidoxime with local conjugate domain for high-efficiency extraction of uranium from seawater

Polyacrylonitrile (PAN) has slow surface dynamics due to its low electron transport capacity, which greatly limits its application in the extraction of uranium (U(VI)) from seawater. Here, we propose a local conjugation domain (LCD) structure between adjacent microdomains of cyclized polyacrylonitrile (CPAN) with different conjugation structures. This structure uses the potential difference between different degrees of conjugate domains to form a built-in field that promotes charge separation. Cyclized polyacrylonitrile amideoxime (CPAO) formed by hydrolyzing the cyano groups that are not involved in conjugation in CPAN can better capture the U(VI) in seawater. After floating in marine for 30 days, the U(VI) extraction capacity of CPAO can reach 5.2 mg g⁻¹, which is 3 times that of PAO. This LCD strategy can be extended to other conjugated high-molecular polymers, thereby it is proposed as a general method for rational design of efficient seawater U(VI) extraction materials.