One-step preparation and characterization of an imidazolium-contained fluorocarbon surfactant and its potential application in aqueous film-forming foam

Preparing fluorocarbon surfactant for aqueous film-forming foam is a complex process. Overcoming steric hindrance when introducing imidazolium to the fluorocarbon chain is a key challenge. In this significant work, we proposed a simple one-step route to prepare imidazolium-contained fluorocarbon surfactant under mild conditions. The FT-IR, 1H NMR, 13C NMR, MS, and TG technologies characterized the imidazolium-contained fluorocarbon surfactant by analyzing functional groups, molecular weight, and thermal stability. An equimolar mixture of imidazolium-contained fluorocarbon surfactant and C6H13NaO3S demonstrated high surface activity, enabling the foam to spread effectively on commercial fuels. The spreading coefficient of foam on n-cyclohexane met the US Military Specification. Coordinatively, the foam drained in time to maintain the stability and completeness of the aqueous layer, with a moderate 25% drainage time of 317 s and a proper foam expansion ratio of 10.5. In extinguishing experiments, the imidazolium-contained fluorocarbon surfactant/C6H13NaO3 mixture extinguished test fires in 65 s, suggesting an essential potential in the aqueous film-forming foam formula.