Unravelling micellar structure and dynamics in an unusually extensive DDAB/bile salt catanionic solution by rheology and NMR-diffusometry

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Mohamed Youssry (Author) Other; Luigi Coppola (Author) Other; Eduardo F Marques (Author) FCUP; Isabella Nicotera (Author) Other

Journal

Title: Journal of Colloid and Interface Science

Vol. 324 No. 1-2

Pages: 192-198

ISSN: 0021-9797

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 18 Citations

Scopus - 17 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-XC7

DOI: 10.1016/j.jcis.2008.04.048

Abstract (EN): The mixed didodecyldimethylammonium bromide (DDAB)-sodium taurodeoxycholate (STDC)-(H2O)-H-2 catanionic system forms a large isotropic (L-1) phase at 25 degrees C. The evolution of microstructure along different dilution lines has been followed by means of rheology and NMR diffusometry. In general, the L, phase is characterised by a weak viscoelasticity and Newtonian response. In the STDC-rich regime (W-s = [DDAB]/[STDC] = 0.2), 5 wt% is an overlapping concentration at which the discrete-to-rodlike micellar transition occurs as indicated from the total surfactant concentration (C-s) dependency of both zero-shear viscosity (eta(0) similar to C-s(3.7)) and surfactant self-diffusion (D-s similar to C-s(-3.0)). As the surfactant molar ratio (W-s >= 1) increases, i.e., DDAB concentration increases, and at constant C-s, eta(0) decreases and D-s increases, indicating the formation of a multiconnected micellar network. (c) 2008 Elsevier Inc. All Fights reserved.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7