Collaborative Research: Molecular and Nanoscale Structure and Interactions of PFAS at Interfaces and Mixed Surfactant Systems

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Per- and polyfluoroalkyl substances (PFAS), also known as “Forever Chemicals,” find a wide variety of applications because of their high chemical and thermal stability and their unique abilities to render solid surfaces non-stick, stabilize foams for firefighting, and be immiscible with both water and hydrocarbons. Released into the environment, PFAS bioaccumulate, resist degradation, and can cause adverse health effects. These factors drive initiatives to reduce future releases of PFAS and to sequester PFAS released in the past. With a goal of developing knowledge that supports improved water quality and the design of functional materials with tailored properties, this project will investigate PFAS surfactants in aqueous solutions and at water-air, water-oil, and water-solid interfaces. The project will develop fundamental knowledge on PFAS properties that can positively impact the environment (use of fluorinated surfactants more efficiently and in smaller amounts, remediation of fluorinated surfactants), health (how fluorocarbon surfactants interact with hydrocarbon surfactants and (bio)polymers), and technology (rational design of new materials and methods for sequestering PFAS, and computational evaluation of new chemical designs for potential replacements of PFAS in products). The coupling of the materials-by-design research with environmental, health, and societal impacts will be integrated into concerted efforts toward outreach and education of scientists and engineers through the engagement of undergraduate students in research and the development of new course materials.Per- and polyfluoroalkyl substances (PFAS) include fluorinated surfactants which find a wide variety of applications because of their high chemical and thermal stability and their unique ability to modify surfaces. PFAS surfactants can be extremely resistant to degradation in the environment, can bioaccumulate, and may cause adverse health effects. This project is a concerted computational and experimental effort that addresses molecular, nano-scale organization of PFAS in bulk water and at interfaces. The research is organized into three topics of study: (1) Competitive molecular interactions and self-assembly of PFAS with other molecules present in aqueous solution: mixtures of different PFAS, and mixtures of PFAS and hydrocarbon surfactants. (2) Organization and interactions between PFAS and hydrocarbon surfactants at the water-air and water-oil interfaces. Such fundamental understanding of PFAS behavior at interfaces is crucial to advance their replacement in key applications such as aqueous film-forming foams (AFFF), and to optimize PFAS sequestration methods such as foam fractionation and aeration. (3) PFAS interactions and binding to model solid surfaces that pertain to the fate of PFAS in the environment and the replacement of PFAS that are used to render surfaces non-stick. The project will generate new knowledge on interactions and self-assembly of systems containing a distribution of PFAS and hydrogenated surfactants; molecular scale insight of PFAS behavior at complex liquid-liquid, air-liquid, and liquid-solid interfaces; and advanced understanding of the role of PFAS surfactants in interfacial properties that define a wide range of technological applications. This fundamental knowledge supports improved water quality and the design of functional materials with tailored properties. The coupling of materials-by-design research with environmental, health, and societal impacts will form the basis of concerted efforts toward outreach and education of early career scientists and engineers through the engagement of undergraduate students in research and the development of new course materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.