Influence Mechanism of Nanoparticles on the Stability of Foam Liquid Films

This study aims to reveal the influence mechanisms of particles to provide a basis for screening high-efficiency foam stabilizers of nanoparticle (NP) and surfactant (SF). Molecular simulation was used, including Stretching Molecular Dynamics (SMD) for liquid film rupture, Mean Squared Displacement (MSD)/Radial Distribution Function (RDF) for water molecule behavior, NP interface tendency analysis, and interface traction force analysis. The system used silica (SiO2) NPs (silane-modified to adjust hydrophilicity–hydrophobicity), three SFs [DTAB, CHSB, BS12; single/mixed systems], water (liquid phase), and nitrogen (gas phase). NPs need balanced hydrophilicity (to adsorb water) and hydrophobicity (to stay at the gas–liquid interface); 10% silane-modified NPs performed best, with 44% higher critical traction force for film rupture than unmodified NPs, effective water adsorption (molecules within 0.3–0.4 nm), and 12% interface presence probability. SFs (especially mixed systems like DTAB + BS12) attracted NPs to form stable composites, binding more tightly than single SFs and reducing SF mobility. The NP-SF system showed superior stability: DTAB + BS12 + NPs had the highest critical traction force (816.11 kJ·mol−1·nm−1) and longest rupture time (1.61 ns); the traction work required to pull NPs in the composite (2443.87 kJ·mol−1) was much higher than that required for pure NPs (991.63 kJ·mol−1). Finally, an experiment was conducted to measure the initial foam volume and drainage half-life of different systems to verify the simulation results.