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Rare earth elements (REEs) are crucial for clean energy technologies but are predominantly purified by solvent extraction using strong acids. This work explores two adsorbents with selective chemistry based on lanmodulin-derived peptides. Two membrane adsorber platforms were synthesized: (1) a poly(vinylbenzyl chloride) membrane with a grafted poly(allyl methacrylate) network and (2) a poly(arylene ether sulfone)membrane with allyl pendant groups. Both membrane adsorbers were functionalized with LanM1 peptides via a thiol−ene click reaction. The morphology, surface chemistry, and adsorption of select trivalent lanthanides (La, Ce, Pr, Nd) were characterized in pH 4−5 solutions, mimicking phosphogypsum waste streams. Results from the adsorption experiments indicate that the lanmodulin peptide sequence maintains its ability to bind when it is immobilized on the surface of polymer fibers for some ions. Despite the different adsorbent designs, the measured capacity of both adsorbents is on the same order of magnitude, which may be explained by differences in the surface area of the fibers 

Rare earth elements (REEs) are a vital part of many technologies with particular importance to the renewable energy sector and there is a pressing need for environmentally friendly and sustainable processes to recover and recycle them from waste streams. Functionalized polymer scaffolds are a promising means to recover REEs due to the ability to engineer both transport properties of the porous material and specificity for target ions. In this work, REE adsorbing polymer scaffolds were synthesized by first introducing poly(glycidyl methacrylate) (GMA) brushes onto porous polyvinylidene fluoride (PVDF) surface through activator generated electron transfer atom transfer radical polymerization (AGET ATRP). Azide moieties were then introduced through a ring opening reaction of GMA. Subsequently, REE-binding peptides were conjugated to the polymer surface through copper catalyzed azide alkyne cycloaddition (CuAAC) click chemistry. The presence of GMA, azide, and peptide was confirmed through Fourier transform infrared spectroscopy. Polymer scaffolds functionalized with the REE-binding peptide bound cerium, while polymer scaffolds functionalized with a scrambled control peptide bound significantly less cerium. Importantly, this study shows that the REE binding peptide retains its functionality when bound to a polymer surface. The conjugation strategy employed in this work can be used to introduce peptides onto other polymeric surfaces and tailor surface specificity for a wide variety of ions and small molecules. 

Abstract Surface-grafted elastin has found a wide range of uses such as sensing, tissue engineering and capture/release applications because of its ability to undergo stimuli-responsive phase transition. While various methods exist to control surface grafting in general, it is still difficult to control orientation as attachment occurs. This study investigates using an electric field as a new approach to control the surface-grafting of short elastin-like polypeptide (ELP). Characterization of ELP grafting to gold via quartz crystal microbalance with dissipation, atomic force microscopy and temperature ramping experiments revealed that the charge/hydrophobicity of the peptides, rearrangement kinetics and an applied electric field impacted the grafted morphology of ELP. Specifically, an ELP with a negative charge on the opposite end of the surface-binding moiety assembled in a more upright orientation, and a sufficient electric field pushed the charge away from the surface compared to when the same peptide was assembled in no electric field. In addition, this study demonstrated that assembling charged ELP in an applied electric field impacts transition behavior. Overall, this study reveals new strategies for achieving desirable and predictable surface properties of surface-bound ELP.