The interfacial diffusion coefficients that resulted from fitting a diffusional relaxation model to surface elasticity values obtained with Surface Light Scattering (SLS) reflect the molecular dynamics of the subphase near the interface. As such, we obtained the viscoelastic properties (surface elasticity and surface viscosity) of monolayers formed by isomers of octyl glucoside and 2-ethylhexyl glucoside surfactants at sub-micellar concentrations. Diffusional relaxation models described the observed trends in high-frequency, non-intrusive SLS.

The nature of the surface at which the surfactant adsorption takes place mainly influenced the interaction forces at low surface coverage. Once a densely packed surfactant layer was formed, it was the surfactant itself that determined the interaction forces.

We measured long-range and adhesive forces acting between non-polar surfaces coated with sugar surfactants. The stability of thin liquid films crucially depended on the surfactant's bulk concentration (c) and thus on the packing density and viscoelasticity of the adsorbed layer. The force barrier preventing removal of the surfactant layer from between two solid-liquid interfaces increased with increasing c, while for foam films it is the stability of the Newton black film that increased with c.