Aqueous film-forming foams (AFFF) containing perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been used for the past 5-6 decades by the Department of Defense (DoD) in fuel fire suppression operations. The  complete elimination of PFOA and PFOS chemicals along with certain C6 substances necessitates the development of  PFAS-free alternatives to replace PFOA/PFOS in firefighting foam formulations.

In this project, specifically, functionalized siloxane-based surfactants were synthesized, and their chemical stability, physical properties, and fire suppression abilities were evaluated. The tests included benchtop testing, 28-ft² fire performance, spreading coefficient, and aquatic toxicity of the foam formulations.

A number of trisiloxane surfactants have been synthesized and successfully tested for their fire fighting capabilities, to enable the spontaneous formation of a water film on top of the fuel. The additives play a critical role in the extinction of fire and stability in water. The performance of trisiloxane surfactants are encouraging and have the potential to replace fluorine-containing AFFF. Further optimization of additive formulations are expected yield a PFAS-free formulation that can replace current AFFF.

PFAS-free formulations developed in this effort have potential as "drop-in" replacement for AFFF products and can meet the performance specifications of the fire extinguishing agent, based on MIL-PRF-24385F standard with further optimization of the formulations. (Project Completion - 2020)