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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 43: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)

CPP 43.4: Talk

Thursday, March 21, 2024, 15:45–16:00, H 0107

Curvature-dependent adsorption of surfactants in water nanodroplets: Insights from molecular dynamics — •Fabio Staniscia and Matej Kanduč — Department of Theoretical Physics, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia

Adsorption of surfactants at curved air-water interfaces plays a major role in phenomena involving nanodroplets, such as emulsification, wetting, heterogeneous catalysis, and aerosol chemistry. Once the nanodroplet becomes small enough, its large curvature can influence the adsorption of surfactants, which has not been thoroughly investigated. At this scope we investigate the adsorption of short-chain surfactants inside water nanodroplets using molecular dynamics simulations. We show that the curvature of the droplet interface enhances adsorption and affects other interfacial properties, such as the preferred surfactant orientation. We relate this behavior to curvature-dependent surface tension of water, described by the Tolman length correction. We show that the influence of curvature on adsorption grows exponentially with the size of the hydrophobic tail of the surfactant. Finally, we use our theoretical model to predict the behavior of larger surfactants and of larger droplets.

Keywords: adsorption; solvation; droplets; molecular dynamics simulation