Pulse radiolytic investigation of perfluorinated surfactants in aqueous solutions

Pulse radiolysis studies were performed for aqueous solutions of ammonium p erfluorooctanoate, tetraethylammonium perfluorooctyl sulfonate, and an ammo nium salt of a carboxylic perfluoropolyether derivative. The protiated syst em of sodium octanoate was also examined for comparison. The rate constants of hydrated electron (e(aq)(-)) and (OH)-O-. radical reactions with these amphiphiles, and absorption spectra of the intermediate products are report ed for the first time. It is demonstrated that the critical micellar concen trations (CMC) can be determined from the kinetic data. The observed differ ences in e(aq)(-) reactivity towards fluorinated amphiphiles above CMC are rationalized in terms of different charge density at the micellar interface .