Chemical Sciences Division, Physical Sciences Directorate, Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, Oak Ridge, TN 37831, USA.
Phys Chem Chem Phys. 2019 Jan 2;21(2):554-560. doi: 10.1039/c8cp02198h.
Emergence is complex behavior arising from the interactions of many simple constituents that do not display such behavior independently. Polyamidoxime (PAO) uranium adsorbents show such phenomena, as recent works articulate that the polymer binds uranium differently than the monomeric constituents. In order to investigate the origins of this emergent uranium-binding behavior, we synthesized a series of amidoxime polymers with low polydispersity and small molecules with lengths ranging from 1 to 125 repeat units. Following immersion in a uranyl-containing solution, the local, intermediate, and macroscopic structures were investigated by X-ray absorption fine structure (XAFS) spectroscopy, small angle neutron scattering (SANS), and dynamic light scattering (DLS). Fits of the extended XAFS (EXAFS) region revealed a progressive change in uranium coordination environment as a function of polymer molecular weight, identifying chain length as a driving force in emergent metal binding and resolving the controversy over how amidoxime adsorbents bind uranium.
涌现是由许多简单成分相互作用产生的复杂行为，这些成分本身并不表现出这种行为。聚酰胺氧肟（PAO）铀吸附剂就表现出了这种现象，因为最近的研究表明，聚合物与单体成分结合铀的方式不同。为了研究这种新兴的铀结合行为的起源，我们合成了一系列低分散度的偕胺肟聚合物和长度从 1 到 125 个重复单元的小分子。将其浸入含有铀的溶液后，通过 X 射线吸收精细结构（XAFS）光谱、小角中子散射（SANS）和动态光散射（DLS）研究了局部、中间和宏观结构。扩展 XAFS（EXAFS）区域的拟合结果表明，随着聚合物分子量的变化，铀配位环境发生了渐进变化，确定链长是新兴金属结合的驱动力，并解决了偕胺肟吸附剂结合铀的方式的争议。
