Scientists Develop Smart Polymers for Sustainable Rare Earth Recovery
Rare earth elements, also known as lanthanides, are essential for modern technology and used in everything from smartphones to electric vehicles. A team of UNC Chemistry professors has designed “smart” polymers that can selectively extract these valuable elements from solutions and could pave the way for a more sustainable and cost-effective way to obtain these crucial materials.
March 3, 2025 I By Dave DeFusco
Rare earth elements, also known as lanthanides, are essential for modern technology and used in everything from smartphones to electric vehicles; however, extracting them efficiently remains a major challenge. A team of researchers, led by Dr. Abigail Knight, assistant professor in the Department of Chemistry at UNC-Chapel Hill, has designed “smart” polymers that can selectively extract these valuable elements from solutions and could pave the way for a more sustainable and cost-effective way to obtain these crucial materials, according to the study, “Structure−Function Insights into Thermoresponsive Copolymers as Lanthanide Precipitants,” recently published in the Journal of the American Chemical Society.
“Lanthanides are difficult to separate because they have similar chemical properties,” said Dr. Knight, who is senior author of the paper. “Current industrial methods, such as solvent extraction and ion-exchange chromatography, are expensive and resource-intensive, so we’re now turning to advanced materials, such as specially designed polymers, to develop a more efficient and environmentally friendly approach.”
The team leveraged the properties of stimuli-responsive polymers, which change in response to external factors like temperature, to engineer materials to bind with lanthanides and then aggregate, forming large particulates that are easy to separate. The addition of hydrophobic components in the polymer also aids in the separation process by conferring a protein-like structure and influencing how the polymer interacts with metal ions.
By adjusting the amount of the hydrophobic component, the researchers could fine-tune how well the polymer extracted lanthanides from a solution. The polymer works by first binding to the lanthanide ions in water and, over time, aggregates with other polymers bound to metal, forming clumps that are enriched in lanthanides. This solid polymer-lanthanide complex can then be removed from the solution to efficiently recover the metal ions. The material, after releasing the lanthanides, can even be reused for additional collection.
“To measure how well our polymer worked, we used a special dye that changes color when it binds to lanthanides,” said Supraja Chittari, the paper’s lead author and a Ph.D. candidate in Chemistry. “Our experiments found that increasing the hydrophobic component of the polymer improved its ability to extract lanthanides. Additionally, the polymer showed metal selectivity, meaning it captured lanthanides while ignoring other common metal ions like calcium.”
This research is an important step toward developing cost-effective, sustainable methods for extracting rare earth elements. By fine-tuning polymer design, scientists can create materials that work more efficiently and selectively. Future research may explore how different polymer structures affect extraction or how these materials can be scaled up for industrial use.
“The ability to engineer responsive polymers for metal sequestration opens new possibilities not just for rare earth elements but for many other critical materials needed in technology and medicine,” said Dr. Knight. “With continued advancements, these polymers could revolutionize how we obtain and recycle valuable resources, making modern technology more sustainable.”