Effect of nanoparticles on spontaneous Ouzo emulsification

Area of Science:

• Colloid and Surface Science
• Materials Science
• Physical Chemistry

Background:

• Particles stabilize fluid interfaces, leading to Pickering emulsions with limited coalescence.
• Increasing particle concentration typically yields smaller droplets in oil/water Pickering emulsions.

Purpose of the Study:

• To investigate the effect of hydrophobic nanoparticles on submicronic droplets in an Ouzo system.
• To characterize droplet size distributions in water/tetrahydrofuran (THF)/butylated hydroxytoluene (BHT) systems using Nanoparticle Tracking Analysis (NTA).

Main Methods:

• Utilized Nanoparticle Tracking Analysis (NTA) for fine characterization of droplet size distributions.
• Investigated the water/THF/BHT phase diagram in the presence and absence of hydrophobic nanoparticles (<10 nm, alkyl-coated).

Main Results:

• Identified Surfactant-Free Microemulsion (SFME) and Ouzo domains, characterizing the transition via droplet size distributions.
• Demonstrated that nanoparticles limit coalescence in the metastable Ouzo domain.
• Confirmed irreversible attachment of alkyl-coated nanoparticles to the liquid-liquid interface.

Conclusions:

• Hydrophobic nanoparticles effectively limit coalescence in metastable Ouzo systems.
• Irreversible nanoparticle adsorption at interfaces enhances emulsion stability.
• NTA provides superior resolution for characterizing droplet size distributions compared to DLS.