A Small-Angle Neutron Scattering Study of Micelles Formed in Aqueous Mixtures of a Nonionic Alkylglucoside and an Anionic Surfactant


The size and shape of micelles formed in aqueous mixtures of the anionic surfactant sodium dodcyl sulfate (SDS) and the nonionic sugar based surfactant n-decyl b -D–glucopyranoside (C10G) at different concentrations of added salt have been investigated with small-angle neutron and static light scattering. Rather small prolate ellipsoidal micelles form in the absence of added salt and in [NaCl] = 10 mM in D2O that grow considerably in length to large rods as the electrolyte concentration is raised to [NaCl] = 0.1 M. In excess of nonionic surfactant ([SDS]:[C10G] = 1:3) in [NaCl] = 0.1 M in D2O several thousands of Angstrom long worm-like micelles are observed. Most interestingly, a large isotope solvent effect was observed from static light scattering data according to which the micelles formed at [SDS]:[C10G] = 1:3 and [NaCl] = 0.1 M in H2O are at least five times smaller than micelles formed in the corresponding samples in D2O.
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