Tracking of Nanoparticle Diffusion at a Liquid-Liquid Interface Adsorbed by Nonionic Surfactants

Area of Science:

• Physical Chemistry
• Colloid Science
• Materials Science

Background:

• Emulsions stabilized by nanoparticles and surfactants exhibit enhanced shelf life.
• Interfacial diffusion mechanisms involving co-adsorbed nanoparticles and surfactants remain poorly understood.

Purpose of the Study:

• To investigate the lateral diffusion of nanoparticles at liquid-liquid interfaces with varying nonionic surfactant concentrations.
• To elucidate the synergistic effects of surfactants on nanoparticle dynamics at interfaces.

Main Methods:

• Single-particle fluorescence tracking was employed to monitor individual hydrophobic nanoparticle diffusion.
• Experiments were conducted at the hexane-glycerol interface with controlled surfactant adsorption.

Main Results:

• Nanoparticle diffusion transitions to a two-regime behavior above a critical surfactant concentration threshold.
• The long-time diffusion regime is characterized by subdiffusion, non-Gaussian behavior, and dynamic anticorrelation.
• Stepwise analysis provided a mechanistic interpretation of the observed diffusion regimes.

Conclusions:

• The study reveals a distinct change in nanoparticle diffusion dynamics influenced by surfactant concentration.
• Findings contribute to understanding the synergistic stabilization mechanisms in surfactant-assisted Pickering emulsions.