CTAB-Silica nanoparticle complexes - dynamic surface tension measurements and modeling

The adsorption dynamics of silica nanoparticles (NP) and cetyltrimethylammonium bromide (CTAB) complexes is studied via dynamic surface properties characterization by the drop Profile Analysis Tensiometry (PAT). Considering the hypothesis that a nanoparticle with a certain number of attached surfactant molecules can be considered as a unified surface-active complex, the equilibrium surface tension for fixed CTAB/NP mixing ratios were considered to construct respective adsorption isotherms. The results can be well described by the Frumkin adsorption model. The fitting parameters of the Frumkin model for different mixing ratios demonstrate that complexes with higher mixing ratios occupy less space at the interface and show weaker interaction with each other.