Entropy-Regulated Dynamics of Surface Tension: Coupling Langmuir Kinetics with High-Precision Tensiometry

Dynamic surface tension γ( t ) is widely measured but often interpreted with system-specific models that obscure general design rules. We develop a minimal kinetic–thermodynamic framework that couples two-rate adsorption–desorption with the Gibbs adsorption relation and Arrhenius temperature dependence, and validate it on ionic (SDS, CTAB) and nonionic (Tween 80) surfactants by force tensiometry from 10–80 °C (10, 20, 30, 40, 60, and 80 °C) across sub- to supra-CMC concentrations, with full uncertainty propagation. A single closed-form expression reproduces γ( t, T, C b ) with R 2 ≥ 0.99. A Damköhler group, Da γ = k a C b / k d, partitions regimes (desorption-limited 10). Extracted trends show k a increases approximately linearly with C b up to the CMC, while k d ≈ 10 –2 –10 –3 s –1 remains nearly constant; Arrhenius fits yield consistent activation energies, and the entropy-generation rate S ̇ gen = − T –1 d γ/ dt peaks early then relaxes toward zero, confirming thermodynamic consistency. The framework maps raw γ( t ) to rate constants, energy barriers, and regime labels, enabling rational selection of surfactant chemistry, concentration, and temperature to achieve rapid interfacial equilibration in sprays, coatings, emulsification, and related processes.