A small-angle neutron and static light 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 dodecyl sulfate (SDS) and the nonionic sugar-based surfactant n-decyl beta-D-glucopyranoside (C(10)G) 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 at NaCl] = 10 mM in D(2)O. The micelles grow considerably in length to large rods as the electrolyte concentration is raised to NaCl] = 0.1 M. In excess of nonionic surfactant (SDS]/C(10)G] = 1:3) at NaCl] = 0.1 M in D(2)O, several thousands of Angstroms long wormlike micelles are observed. Most interestingly, a conspicuously large isotope solvent effect was observed from static light scattering data according to which micelles formed at SDS]/C(10)G] = 1:3 and NaCl] = 0.1 M in H(2)O are at least five times smaller than micelles formed in the corresponding samples in D(2)O.