Micellar crowding and branching in a versatile catanionic system

The catanionic system didodecyldimethylammonium bromide (DDAB)-sodium taurodeoxycholate(STDC)-D2O is characterized by an exceptionally extended L1region. The comparison of self-diffusioncoefficient of the solvent and the DDAB embedded in the micelles provided information about hydra-tion of the aggregates. Moreover, correlating self-diffusion and14N NMR relaxation measurements newinsight could be obtained regarding the translational and rotational micellar motions in the crowded solu-tions of systems with 0.2 DDAB-STDC molar ratio.1H 2D NMR spectra gave some hints about the mutualarrangement of DDAB and STDC within the aggregates. For samples with 1.8 and 2.6 DDAB/STD molarratios the14N data were in agreement with the presence of somewhat branched, interconnected micelles.23Na and81Br dynamic parameters resulted particularly sensitive to the surrounding environment.The peculiar rheological behaviour of the, highly concentrated, branched micelles samples, namely thesteady oscillations in the step tests, was found to be an example of instability originated by the combinedeffect of material elasticity and slippage at the fixed wall.