Complexation of poly(acrylic acid)s with uranyl ion

Structural Study of Polystyrene-b-poly(acrylic acid) Micelles Complexed with Uranyl: A SAXS Core-Shell Model Analysis

The interactions between natural colloidal organic matter and actinides in solutions are complex and not fully understood. In this work, a crew-cut polystyrene-b-poly(acry1ic acid) (PS-b-PAA) micelle is proposed as a model particle for humic acid (HA) colloid with the aim to better understand the sequestration, aggregation, and mobility of HA colloids in the presence of uranyl ions. The effects of uranyl ions on the structure of PS_29k-b-PAA_5k micelles in aqueous solution were mainly investigated by synchrotron small-angle X-ray scattering. A core-shell model, accounting for the thickness and contrast changes of the PAA corona induced by the adsorption of uranyl, was employed to analyze the scattering data. A combination of transmission electron microscopy, dynamic light scattering, and zetametry showed a strong affinity of uranyl ions to PAA segments in water at pH 4-5 that resulted in the shrinkage and improved contrast of the PAA corona, as well as colloidal destabilization at a high uranyl concentration.

Synthesis and Characterization of Polystyrene-Supported Piperazine-Substituted Triazoles by CuAAC and First Evaluation for Metal Ion Extraction

The goal of this work was to synthesize substituted polystyrene for metal extraction and/or depollution by introduction of substituted piperazines as chelatants starting from Merrifield polymer. After transformation of Merrifield’s resin in azidomethyl polystyrene, click-chemistry using copper (I)-catalyzed Huisgen’s reaction (CuAAC) was performed to prepare different polymers grafted with 1,4-triazoles bearing the piperazines, containing an alkyne as the other counterpart in the CuAAC. The polymers were then first tested for their efficiency to remove various metal ions from neutral aqueous solutions (Fe³⁺, Ni²⁺, Cu²⁺, Zn²⁺ and Pb²⁺). The polymers were found to extract Ni²⁺ and Zn²⁺ with low efficiencies ≤40%. For Fe³⁺ and Cu²⁺, the average extraction was around 80%, and for Pb²⁺ around 50%. The global selectivity for these polymers was found to be in the order of Fe³⁺ ≥ Cu²⁺ > Pb²⁺ >> Ni²⁺ > Zn²⁺.

Complex formation of linear poly(methacrylic acid) with uranyl ions in aqueous solutions

The complex formation of uranyl ions (UO(2+)2) with poly(methacrylic acid) (PMAA) was investigated by potentiometric, conductometric, UV-visible, luminescence and FTIR spectroscopic, and thermal analysis methods. The stoichiometric ratio at complexation between polymer and uranyl ions was found to be equal to 2 polymer base units per uranyl ion. FTIR spectra of the PMAA-UO(2+)2 complex confirmed incorporation of metal ions into the polymer and showed that the electrostatic interactions play a major role in complexation. An increase of emission intensity in luminescence spectra of uranyl ions suggests influence of conformation peculiarity of the poly(methacrylic acid) chain. The thermal degradation of polycomplex starts at lower temperature as compared to pristine PMAA that is due to the lower thermal stability of PMAA-UO(2+)2 complex.