Pulse radiolytic investigation of perfluorinated surfactants in aqueous solutions

Pulse radiolysis studies were performed for aqueous solutions of ammonium perfluorooctanoate, tetraethylammonium perfluorooctyl sulfonate, and an ammonium salt of a carboxylic perfluoropolyether derivative. The protiated system of sodium octanoate was also examined for comparison. The rate constants of hydrated electron (e⁻ _aq) and ^·OH radical reactions with these amphiphiles, and absorption spectra of the intermediate products are reported for the first time. It is demonstrated that the critical micellar concentrations (CMC) can be determined from the kinetic data. The observed differences in e⁻ _aq reactivity towards fluorinated amphiphiles above CMC are rationalized in terms of different charge density at the micellar interface.