(409a) Nanoparticle Adsorption Dynamics at Fluid Interfaces

Frechette, J., Johns Hopkins University
Hua, X., Johns Hopkins University
Bevan, M. A., Johns Hopkins University
Understanding the dynamic adsorption of nanoparticles (NPs) at fluid interfaces is important for stabilizing emulsions and for the preparation of 2D NPs-based materials. Here we show that the Ward-Tordai equations commonly employed to describe the dynamic of surfactant adsorption at a fluid interface combined with a Frumkin adsorption isotherm can be employed to model the diffusion-limited adsorption of NPs onto a fluid interface. In contrast to surfactants, an additional wetting equation of state (EOS) must be incorporated to characterize the dynamic interfacial tension during the adsorption of NPs to the oil-water interface. Our results show agreement between the model and experiments at NP area fraction < 0.3. Slower dynamics are observed at larger area fractions, which are speculated to arise from polydispersity or re-organization at the interface. We show the model can be extended to the competitive adsorption between the NPs and a surface active species.