The unique interactions between organic molecules at liquid-liquid interfaces, which enable cell formation through the self-assembly of supramolecular structures, can serve as inspiration for engineers to design new materials with similar functions to those seen in nature. By marrying the properties of certain inorganic chemicals with those of organic substances, bio-inspired materials can offer promising solutions to problems ranging from health conditions to pollution. A team of researchers from Pennsylvania State University (Penn State) have developed a new material with interfacial self-assembly capabilities that incorporates fluorine to capture and easily remove PFAS contaminants from water.
The researchers utilized a fluorinated oil to guide the molecular organization of fluorinated amino acids in water, resulting in a material that changes structure on its own based on mechanical stimuli. When the oil was first added to the water, it formed a bead comprised of a fluorine droplet surrounded by an amino acid coating, and when the vial was inverted to expose the bead to air, it rearranged itself into a film composed of a thin layer of fluorinated oil surrounded by two layers of crystalline amino acid structures. The material would then reform into a bead when agitated.
The Penn State team became interested in testing the material’s potential to capture pollutants in water for easy removal. Fluorous compounds like per- and polyfluoroalkyl substances (PFAS) tend to gravitate toward other fluorine-containing substances, such as the fluorinated amino acid material. The researchers added water contaminated with PFAS to a plastic container coated with the fluorinated amino acid film and found that the film captured the PFAS within two hours and could hold them for up to 24 hours. After capturing the contaminants, the film was agitated to form a bead that was easily collected from the water. The study was published in Advanced Functional Materials.
“There’s a lot of effort being placed into investigating the toxicology of PFAS and how to regulate them. This material could be implemented to remove PFAS from drinking water — and we think it could have a lot of utility in other areas as well,” said corresponding author Scott Medina.
The researchers plan to further explore the ability of the fluorinated material to purify water and potentially extract compounds from air as well.