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A Microtensiometer To Probe the Effect of Radius of Curvature on Surfactant Transport to a Spherical Interface
Journal article   Peer reviewed

A Microtensiometer To Probe the Effect of Radius of Curvature on Surfactant Transport to a Spherical Interface

Nicolas J. Alvarez, Lynn M. Walker and Shelley L. Anna
Langmuir, v 26(16), pp 13310-13319
17 Aug 2010
PMID: 20695573

Abstract

Chemistry Chemistry, Multidisciplinary Chemistry, Physical Materials Science Materials Science, Multidisciplinary Physical Sciences Science & Technology Technology
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 mu m, 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.

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Web of Science research areas
Chemistry, Multidisciplinary
Chemistry, Physical
Materials Science, Multidisciplinary
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