Surface and foam property of perfluoroalkyl polyoxyethylene ether phosphate salt in aqueous-ethanol system

Abstract Foam is used in many fields with excellent performance. Moreover, disinfectants with ethanol as the main ingredient have increasingly been used in people's lives. However, the foam research of an ethanol-water mixed system is still in the initial stage. In this work, a perfluoroalkyl polyoxyethylene ether phosphate salt surfactant (FEP-Na) was synthesized through a new molecular design. The surfactant has good interfacial adsorption behavior in 50% ethanol-water mixing system, and the approximately spherical aggregates are observed in the volume phase of the solution. Moreover, FEP-Na showed good foaming property in 50% ethanol-water mixed solution. Interestingly, high concentration solutions with high surface activity have lower foam stability. And under the microscope, we see that the bubble burst is dominated by the phenomenon of coalescence. In this regard, we explain the mechanism of foam stability by electrostatic double layer theory and interfacial dilation rheology. It provides a new choice for the synthesis of foaming agent in the ethanol-water mixed system at a concentration of 50%.