| Abstract
| - Aqueous salt solutions containing elongated micelles of sodium dodecyl sulfate (SDS) have been studiedat 45 °C using small-angle neutron scattering. At NaCl concentrations in the 1−2 M range, the scatteringdata are consistent with semiflexible rather than rigid rodlike micelles, and this conclusion is consistentwith previous studies of SDS micelles using small-angle scattering. However, until now quantitativedeterminations of micellar flexibility, that is, of persistence lengths, especially as a function of ionic strength,have not been available. By making measurements in the range of scattering vectors appropriate for thislength scale and by incorporating the effect of intermicellar interactions into the fitting protocol, it hasbeen possible to determine persistence lengths accurately. Partitioning of the values into intrinsic andelectrostatic components is discussed, and the results are compared with data for the highly flexibleanionic polyelectrolyte sodium polystyrenesulfonate. The one-dimensional bending moduli for the flexibleSDS micelles are compared to the analogous two-dimensional bending moduli for SDS bilayers.
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