Reversible adsorption of nanoparticles at surfactant-laden liquid-liquid interfaces

In this study, we show that hydrophilic nanoparticles can readily desorb from liquid-liquid interfaces in the presence of surfactants that do not change the wettability of the particles. Our observations are based on a simple theoretical approach to assess the number of adsorbed particles at the surfactant-laden liquid-liquid interface. We test this approach by studying the interfacial self-assembly of equally charged particles and lipids dissolved in separate immiscible phases. Hence, we investigate the interfacial adsorption of aminated silica particles (80 nm) and octadecyl amine (ODA) to the decane/water interface by interfacial tension measurements which are supplemented by interfacial rheology of the adsorbed interfacial films, SEM-micrographs of Langmuir-Blodgett films and measurements of the three-phase contact angle of the particle-surface in the presence of surfactants. The measurements show that particles adsorb at the surfactant-laden interface at all investigated surfactant concentrations and...