Speaker
Description
Adsorption of surfactants to fluid interfaces occurs in technological and daily-life contexts. The surfactant surface coverage $\Gamma$ governs interface characteristics like tension $\gamma$, viscoelastic properties, and the stability of thin foam films. Typical experiments merely yield the tension isotherm $\gamma(c)$, where $c$ is the bulk concentration. Parameter-based models of surfactant adsorption therefore rely on thermodynamic relations between $\gamma(c)$ and the adsorption isotherm $\Gamma(c)$, which are, however, often impractical, so that a direct determination of $\Gamma$ is desirable. We combine various scattering techniques with atomistic molecular dynamics (MD) simulations for the determination of $\Gamma$ for single- and two-component surfactant solutions. Moreover, with the help of free energy calculations in MD simulations we predict $\gamma(c)$ curves for direct comparison and validation with available experimental data. Finally, we combine grazing-incidence X-ray diffraction with MD simulations to characterize structural correlations in surfactant adsorption layers.
