Aggregation of perfluorinated polymers in aqueous solution studied by ESR

Abstract The aggregation of perfluoropolyethers (PFPE) of the general formula CF 3 [OCF 2 CF (CF 3 ) 3-4 OCF 2 COOH in water (in the form of the ammonium salt) has been studied by ESR of a small cationic nitroxide, TempTMA + , which is able to interact electrostatically with the aggregate surface. The ESR lineshapes were computed assuming strongly anisotropic motion, which is typical of partially ordered systems. Lineshapes and hyperfine coupling constants were used to determine the micelle formation and to evaluate approximately the aggregation number.