The electrostatic interaction between nanoparticles and surfactants with complementary groups promotes the liquid film rupture

The stability of the liquid film is determined by the van der Waals force and the electrical double layer force, which dictates the termination of the liquid film drainage process. The liquid film drainage is the rate-determining step of the thermodynamic interactions between droplets and interfaces, including droplet coalescence, adsorption, and cross-phase transfer. The interaction between nanoparticles and surfactants has great potential in influencing the stability of liquid film. When nanoparticles and surfactants are adsorbed on the two interfaces of liquid film respectively, an electrical double layer force is generated to attract or repel the two interfaces based on the charges’ polarity. Consequently, we verified the electrostatic interaction between nanoparticles and surfactants experimentally. Subsequently, the effect of electrical double layer force on liquid film rupture was validated by analyzing the dynamics of droplet adsorption. Finally, the intensification of droplet adsorption in a microchannel was realized by utilizing this mechanism. This study establishes a fundamental framework for precise regulation of interfacial forces at the scale of liquid film thickness, thereby providing a novel approach to investigate soft matter.