Vesicle phases from alkyldimethylaminoxides and strong acids.: The Hofmeister series of anions and the L1/Lα-phase transition

It is shown that the hydrophilicity of the alkyldimethylaminoxide surfactants passes with increasing protonation through a minimum. Both the unprotonated species and the completely protonated species are less surface active than the mixture of the species. The properties of the micellar solutions depend also very much on the acid that is used for the protonation. For strong hydrophilic acids like HCl or formic acid the micellar solutions remain in the L-1-phase. For acids the counter-ions of which can shield ionic charges very well like HClO4 the micellar solutions pass with increasing protonation from the L-1 to the L-alpha-phase and back to the L-1-phase. (C) 2004 Elsevier Ltd. All rights reserved.