Use of a Nitroxide Spin Probe to Study the Structure of the Adsorbed Layer of Dodecyl Sulfate at the Alumina-Water Interface

摘要

A nitroxide spin probe is used to examine the process of hemimicelle formation of the anionic surfactant sodium dodecyl sulfate (SDS) adsorbed on alumina by ESR spectroscopy of the slurry. It is found that, at low SDS concentrations, the probe itself aggregates on the surface. As the SDS concentration is raised such that SDS hemimicelles form, the probe aggregates are broken up, and the resulting ESR spectrum is consistent with the nitroxide being within the SDS hemimicelles with a local viscosity of 120-165 cP.