Journal
SOLID STATE NUCLEAR MAGNETIC RESONANCE
Volume 22, Issue 2-3, Pages 394-408Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1006/snmr.2002.0087
Keywords
-
Ask authors/readers for more resources
Tortuosity, 1/alpha, and surface-to-volume ratio, S/V, were determined in aqueous solutions of decylammonium, dodecylammonium and tetradecylammonium chlorides of various concentrations by measuring the apparent diffusion coefficient of water, D-app(Delta). This was found to be much smaller than in the bulk state. Such restricted diffusion is interpreted in terms of the Mitra model, where D(A) depends on diffusion time and is controlled primarily by S/V. The samples exhibit lamellar (L), hexagonal (H) and isotropic (1) liquid crystalline phases. We observed changes in S/V upon phase transition. In the lamellar and hexagonal phases, the system is ordered, resulting in relatively small S/V ratios, compared to the micellar-isotropic phase. We did not observe a dependence on the diffusion time, A, in the isotropic phase, because the duration of the experiment was not sufficiently short to observe the change from Dapp(A) to Den. We observed the effective diffusion coefficient of water, which directly probes the tortuosity of the system. The S/V ratios were obtained by fitting the Mitra model, using known values of the bulk water diffusion coefficients, and the assumption that D-app --> D-0 for Delta --> 0. S/V is correlated with the type of structure, increasing on transition to the isotropic phase and decreasing on transition to other phases. The change in tortuosity is small, but slightly larger for the isotropic phase. (C) 2002 Elsevier Science (USA).
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available