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Studies on an ester-modified cationic amphiphile in aqueous systems: Behavior of binary solutions and ternary mixtures with conventional surfactants

Dan Lundberg (Institutionen för kemi- och bioteknik, Teknisk ytkemi) ; Johan Unga (Institutionen för kemi- och bioteknik) ; A. L. Galloway ; F. M. Menger
Langmuir (0743-7463). Vol. 23 (2007), 23, p. 11434-11442.
[Artikel, refereegranskad vetenskaplig]

The aqueous behavior of an ester-modified cationic amphiphile with the molecular structure CH3CH2O(C=O)(CH2)(6)(C=O)O(CH2)sN+(CH3)(3)Br-, in the following referred to as A, has been investigated. Systems with A as the only solute, as well as different aqueous mixtures with conventional cationic surfactants, primarily dodecyltrimethylammonium bromide (DTAB), were included in the study. Isotropic solution samples were characterized using H-1 NMR, C-13 NMR, NMR diffusometry, and conductivity measurements, whereas liquid crystalline samples were investigated by optical polarization microscopy and small-angle X-ray diffraction. The results are compared to the behavior of the binary system of DTAB and water. A does not exhibit a typical surfactant behavior. When it is present as the only solute in a binary aqueous system, it forms neither conventional micelles nor liquid crystalline phases. However; there is clear evidence that it assembles with lower cooperativity into loose clusters at concentrations above 25-30 mM. When A is mixed with DTAB in solution, the two amphiphiles form mixed assemblies, the structure of which varies with the total amphiphile concentration. In concentrated mixtures with alkyltrimethylammonium surfactants, A can participate in hexagonal liquid crystalline phases even when it constitutes a significant fraction of the total amphiphile content.

Nyckelord: NUCLEAR-MAGNETIC-RESONANCE, STUDYING TRANSLATIONAL DIFFUSION, MICELLAR, SOLUTIONS, SELF-DIFFUSION, FIELD GRADIENT, BROWNIAN PARTICLES, C-13, NMR, WATER, BROMIDE, ASSOCIATION



Denna post skapades 2008-12-10.
CPL Pubid: 80913

 

Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Teknisk ytkemi (2005-2014)
Institutionen för kemi- och bioteknik (2005-2014)

Ämnesområden

Kemiteknik

Chalmers infrastruktur