Regulation of Ostwald ripening behavior through surfactant mixing and droplet mixing strategies in tween-stabilized emulsions

This study elucidates how surfactant mixing strategies regulate Ostwald ripening in Tween-stabilized emulsions. Emulsions stabilized by single Tweens, mixed-surfactant formulations, and mixed-droplet strategies were compared, and corn oil was evaluated as a representative ripening inhibitor. Tween 60 exhibited the highest resistance to droplet growth, whereas Tween 80 showed limited stability despite producing the lowest interfacial tension. The predicted trends in ripening rates did not follow the measured trends in interfacial tension. This may indicate that interfacial packing and mechanical properties govern ripening stability rather than interfacial tension. When using corn oil as an inhibitor, emulsions prepared with mixed surfactants exhibited better stability compared to mixed-droplet emulsions. Based on these findings, mixed-surfactant and mixed-droplet strategies are not kinetically equivalent because surfactant exchange can dynamically redistribute interfacial composition, leading to alter the kinetics of oil mass transfer. Conclusively, controlling surfactant exchange dynamics is as critical as formulation composition for enhancing emulsion stability.