To synthesize new fluorine-free siloxane surfactants and evaluate them by the current U.S. Department of Defense (DoD) specifications (MIL-PRF-24385F) for suppression of jet fuel and gasoline pool fires. The siloxane surfactants could be useful additives or drop-in replacements for the per- and polyfluoroalkyl substances (PFAS) of aqueous film forming foams (AFFF) found in current Class B firefighting technology widely used by DoD.

Investigations found that siloxanes bonded to sugars or glycosiloxanes are excellent surfactants that can spread on the surface of hydrocarbon liquids. This project will synthesize new glycosiloxanes structures using commercially available siloxane precursor chemicals. The glycosiloxanes will be analyzed for how well they decrease the surface tension of water. The glycosiloxanes will be mixed with hydrocarbon surfactants and other solvents to make 3 wt% concentrates. Glycosiloxane concentrates will be screened in 1ft² pan fire tests with jet fuel and gasoline. Foam drainage times (25%) and expansion ratios will be taken on the glycosiloxane premixes. The best surfactant candidates will be scaled-up to generate ~200 g of glycosiloxane surfactant to conduct 28ft² MilSpec pool fire testing.

This new glycosiloxane surfactants could help DoD substitute PFAS in AFFF concentrates since PFAS will be phased out by the FY21 Defense Authorization Bill, starting 1 October 2024. Using glycosiloxane surfactants, it may be possible to extinguish fires with smaller quantities of chemicals than previous fluorinated-AFFF formulations.