2010/07/16 by Nicolas J. Alvarez, Lynn M. Walker, Shelley L. Anna · 2 citations
Engineering · Chemistry · Mathematics · #Material Properties and Processing #Advanced Fiber Optic Sensors #Surfactants and Colloidal Systems #Pulmonary surfactant #Curvature #RADIUS #Radius of curvature #Hydrodynamic radius #Interface (matter) #Chemistry #Materials science #Chemical physics #Nanotechnology #Physics #Mean curvature #Thermodynamics #Geometry #Nanoparticle #Mathematics #Computer science #Dynamic light scattering
paper · doi:10.1021/la101870m
openalex publication_date 2010/07/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
Diffusion of surfactant to a spherical interface depends on the radius of curvature of the interface; the smaller the radius of curvature is, the faster the dynamics. This paper presents and validates an experimental apparatus, denoted a "microtensiometer", to study the dependence of surfactant dynamics on radius of curvature. Dynamic surface tension is monitored for a range of bubble radii from 17 to 150 microm, and the dynamics are compared with those obtained using the classic pendant drop experiment for a nonionic surfactant at the air-water interface. Experiments reveal that dynamic surface tension follows a diffusion-limited scaling, in which radius of curvature is a key parameter. Despite the clear scaling behavior of the experimental equilibration time, the full dynamic curve for an initially clean interface cannot be predicted by a diffusion-limited transport model using the molecular diffusion coefficient and a single isotherm. However, the same model is shown to correctly predict compression-expansion experiments. Aside from elucidation of surfactant transport, this device provides a tool for rapid measurements of interfacial properties using a significantly lower volume of sample than current methods.