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Observing diffusive exchange between surfactant and aqueous domains in detergents
Jonathan D Griffith1, Jonathan Mitchell, Andrew E Bayly
1Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
The Journal of Physical Chemistry. B
|May 15, 2009
Summary
Nuclear magnetic resonance (NMR) revealed water diffusion between surfactant multilamellar vesicles (MLVs). This study quantifies exchange times and distances, offering insights into MLV structure and dynamics in industrial formulations.
Area of Science:
- Materials Science
- Physical Chemistry
- Biophysics
Background:
- Surfactant multilamellar vesicles (MLVs) are crucial in various industrial applications.
- Understanding water dynamics within MLVs is essential for optimizing their performance.
- Nuclear magnetic resonance (NMR) offers non-invasive methods to probe molecular interactions.
Purpose of the Study:
- To investigate water molecule diffusion between domains in surfactant MLVs using advanced NMR techniques.
- To quantify the exchange times and distances governing water transport within MLV formulations.
- To correlate NMR-derived parameters with the structural characteristics of MLVs.
Main Methods:
- Utilized two-dimensional relaxation correlation NMR experiments.
- Correlated transverse T2 relaxation measurements before and after storage intervals.
- Employed chemically selective pulsed field gradient (PFG) NMR to determine diffusion coefficients.
Main Results:
- Observed diffusive exchange of water molecules between different domains within the MLV formulation.
- Determined two average water exchange times: 0.04 s and 0.83 s.
- Calculated exchange distances of 6.2 and 81 micrometers, linked to MLV diameter and potential cluster sizes.
Conclusions:
- NMR relaxation correlation and PFG techniques effectively probe water dynamics in MLVs.
- The determined exchange distances provide quantitative insights into MLV structure and aggregation.
- Findings contribute to the understanding of MLV behavior in industrial aqueous solutions.
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