Temperature Effect on the Nanostructure of SDS Micelles in Water

Published

April 11, 2013

Author(s)

Boualem Hammouda

Abstract

Sodium dodecyl sulfate (SDS) surfactants form micelles when dissolved in water. These are formed of a hydrocarbon core and hydrophilic ionic surface. The small-angle neutron scattering (SANS) technique was used with deuterated water (D₂O) in order to characterize the micellar structure. Micelles were found to be slightly compressed (oblate ellipsoids) and their sizes shrink with increasing temperature. Fits of SANS data to the Mean Spherical Approximation (MSA) model yielded a calculated micelle volume fraction which was lower than the SDS surfactant (sample mixing) volume fraction; this suggests that part of the SDS molecules do not participate in micelle formation and remain homogeneously mixed in the solvent. A set of material balance equations allowed the estimation of the SDS fraction in the micelles. This fraction was found to be high (close to one) except for samples around 1% SDS fraction. The micelle aggregation number was found to decrease with increasing temperature and/or decreasing SDS fraction.

Citation

Journal of Research (NIST JRES) - 118.008

Report Number

118.008

NIST Pub Series

Journal of Research (NIST JRES)

Pub Type

NIST Pubs

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DOI Link

Keywords

Sodium dodecyl sulfate, SDS, SANS, small-angle neutron scattering, micellar structure

Citation

Hammouda, B. (2013), Temperature Effect on the Nanostructure of SDS Micelles in Water, Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/jres.118.008 (Accessed March 25, 2025)