화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.113, No.20, 7156-7161, 2009
Observing Diffusive Exchange between Surfactant and Aqueous Domains in Detergents
Nuclear magnetic resonance (NMR) two-dimensional relaxation correlation experiments have been used to study an industrially relevant formulation of surfactant multilamellar vesicles (MLVs) in an aqueous solution. By correlating transverse T-2 relaxation measurements before and after a storage interval, diffusive exchange of water molecules between domains can be observed. Two average exchange times of 0.04 and 0.83 s were determined by solving the one-dimensional Fredholm integral form of a model for region-to-region exchange. Diffusion coefficients for the restricted and free water fractions within the mixture determined via chemically selective pulsed field gradient (PFG) NMR measurements allowed exchange distances of 6.2 and 81 mu m to be determined from the exchange times. These exchange distances are associated with the average MLV diameter and speculatively with the size of MLV clusters, respectively.