Synergistic Mixture Foam of Sapindus Saponin and Bio‐Based Surfactant: Performance Enhancement and Regulatory Mechanisms

ABSTRACT High‐performance, sustainable foam systems are critical for industrial applications. Natural saponins offer biocompatibility but often require formulation optimization to balance rigidity and wettability. This study investigates the foamability and stability of a composite system comprising Sapindus saponin (SS) and a bio‐based surfactant (JFC‐U). Using surface tension measurements and microscopic tracking, we elucidate the regulatory mechanisms governing foam evolution. Results identify a significant synergistic effect at a 9:1 SS:JU mass ratio, where the equilibrium surface tension is reduced to 22.8 mN/m, suggesting a dense interfacial packing of molecules. This optimal formulation achieves a structural half‐life of 240 min and superior foam volume, effectively balancing exceptional stability with enhanced wetting efficiency. Conversely, a 5:5 ratio exhibits antagonism due to steric hindrance disrupting molecular ordering. To rigorously quantify this performance, a multidimensional foam performance index () was constructed, integrating interfacial (), generation (), and stability () indices. This work establishes a quantitative link between molecular assembly, microscopic destabilization kinetics, and macroscopic longevity, providing a mechanistic basis for designing ultra‐stable, eco‐friendly foams.