Exchange processes in solutions of nitroxide surfactants

Abstract

The temperature-dependent broadening of the electron paramagnetic resonance spectra observed in aqueous solutions of the paramagnetic surfactants 2,2,6,6-tetramethylpiperidine-oxidedecyldi-methylammonium bromide, 2,2,6,6-tetramethylpiperidine-oxidedodecyldimethylammonium bromide and 2,2,6,6-tetramethylpiperidine-oxidetetradecyldimethylammonium bromide is not caused by monomer–micelle exchange in those solutions. It is probably due to the different effectiveness of monomers and micelles in causing Heisenberg spin exchange, complicated by the temperature variation of the c.m.c. and by possible dimerization of the nitroxide head group.