Abstract

An experimental method called dynamic Wilhelmyplate technique (DWPT) for studying dynamic surfacetension was designed in this study. A diffusion-controlled model corresponding to the initial and boundary conditions of this method was proposed. Dynamic surfacetension of Triton X-100 and SDS was measured with this technique and analyzed with the proposed model. The calculated diffusion coefficients for the short- and long-time approximations are 3.7 × 10⁻⁶ and 0.97 × 10⁻⁶ cm²/s for Triton X-100 and 4.6 × 10⁻⁶ and 0.79 × 10⁻⁶ cm²/s for SDS, respectively. The predicted dynamic surfacetension with these diffusion coefficients for the simultaneously generated aqueous/air interfaces is in good agreement with the drop mass technique. Another diffusion controlled model that considers the energy barrier at the aqueous/air interface was also proposed in this study. The calculated energy barriers are in the range of 4.1–5.7 RT for Triton X-100 and 6.5–8.0 RT for SDS.