The structure-activity relationship for the ABA triblock siloxane surfactant in aqueous-ethanol system

It is challenging to improve the foam stability in high concentration ethanol solution. In this paper, well-defined polyether-modified siloxane surfactants were synthesized,and their structures were characterized through infrared spectroscopy and one- and two-dimensional Nuclear magnetic resonance (NMR) spectroscopy. Furthermore, the relationships of between their chemical structure, surface activity, and foam property in high concentration ethanol solution were investigated in detail. The results showed that the target surfactant exhibited an ABA-type structure. They can effectively reduce the surface tension and produce the excellent foam in 75% ethanol. In particular, these surfactants with loner siloxane chain confer strong foaming power in 75% solution. This ability with good surface activity in water-ethanol system suggests a wide range of potential applications in low surface tension solvent system.