Dynamics of Partial Wetting and Dewetting in Well-Defined Systems

By analyzing the assumptions of the hydrodynamic, molecular-kinetic and molecular-hydrodynamic theories of wetting dynamics, we formulated qualitative criteria for their applicability on the basis of the wetting−dewetting asymmetry of the dynamic contact angle/velocity dependence ϑ/V presented on characteristic theoretical scales. The quantitative test concerns the physical plausibility of the values of the microscopic dynamic parameters obtained from the fit of the theoretical equations to experimental data. New ϑ/V data were obtained and used to compare theory and experiment under well-defined conditions close to the assumptions of the theoretical models. The advancing and receding of methanol, ethanol, 1-butanol, and 1-octanol on the amorphous fluoropolymer AF 1600 were studied. The small AFM roughness (0.3−0.4 nm/μm2), static angle hysteresis between 3 and 7°, and reproducibility within ±0.2° of the dynamic contact angles at different contact line positions demonstrate the good quality of the solid su...