The objective of this project is to synthesize and characterize the flame suppression properties of phosphonate-based polymer(s) in a fluorine-free aqueous film forming foams (AFFF) formulation. This fluorine-free AFFF polyphosphonate additive will test the hypothesis that an “intumescence fire-suppression mechanism” can be achieved with the system meeting the fire-extinguishing requirements found in performance specification fire-extinguishing agent, AFFF liquid concentrate for fresh and seawater MIL-PRF-24385(SH) with interim amendments.

During this project, the Naval Air Warfare Center Weapons Division will create an innovative strategy to eliminate fluorine from AFFF with phosphorous containing polymers that can suppress a liquid fire either F-24 fuel or gasoline with an “intumescence fire-suppression mechanism.” The efforts will focus on developing a water based poly(n-alkyl(2-methacrylamidoethyl))phosphonate/phosphonic acid derivatives and non-isocyanate polyurethane containing the unique flame-retardant properties of phosphorus within the backbone of the polymer structure. These fluorine-free AFFF phosphorus containing oligomers and polymers will be capable of forming foams that can be applied via spray forming an aqueous thin foaming film between the air-hydrocarbon liquid fuel interface extinguishing a fire via an “intumescence” mechanism. Once polymers are synthesized/characterized, AFFF formulations based on these phosphonate/phosphonic acid derivatives will be developed and tests comparable to MIL-PRF-24385(SH) will be measured such as refractive index, viscosity (centistokes: maximum at 5^oC, minimum at 25^oC), hydrogen ion concentration (pH), spreading coefficient, foamability, and shelf-life stability. These tests will be conducted at the laboratory scale only and modifications to the MIL-PRF-24385 testing protocols will be implemented. Additional testing will include an initial toxicology study of monomers and polymers, which will be investigated by the Army Public Health Center using quantitative structure-activity relationship models. Finally, the potential health and environmental effects of the oligomers/polymers will be evaluated via the toxicity characteristic leaching procedure to determine if the oligomers/polymers can break down and potentially contaminate ground water/surface waters via leaching. Gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry and high resolution mass spectrometry will be used for analysis of all leachates.

The benefits to the Department of Defense (DoD) and scientific community at large are several fold: a). DoD depots, training grounds, military installations and non-military installations such as municipal airports would benefit from an enhancement of fire suppression performance, b). alternative non-per and polyfluoroalkyl substances (PFAS) formulations that meet current fire extinguishable requirements in MIL-PRF-24385, c). improved performance of foam formation, discharge and delivery would provide viable alternatives to the current reliance on fluorinated AFFFs and non-AFFFs that do not meet current performance fire extinguishing for gasoline fires, d). improved safety for DoD personnel at airfields/depots/training grounds and e). meets environmental (federal/state) requirements for PFAS discharges.