Out of Equilibrium Divergence of Dissipation in an Oscillating Bubble Coated by Surfactants

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• 作者：Mario Corti ; Martina Pannuzzo ; Antonio Raudino
• 刊名：Langmuir
• 出版年：2014
• 出版时间：January 21, 2014
• 年：2014
• 卷：30
• 期：2
• 页码：477-487
• 全文大小：470K
• ISSN：1520-5827

文摘

We report measurements of the relaxation and resonance frequency of forced oscillating bubbles covered by a layer of surface-active molecules, the anionic surfactant sodium dodecyl sulfate (SDS). Less systematic investigations have been also carried out on neutral and cationic surfactants. A divergence of the viscous damping is observed at a very low bulk concentration. Subtle variations in the resonance peak are also measured. Bubble oscillations are driven by an electric field and measured with a sensitive interferometric technique. Results are interpreted with a model which takes care of the coupling between the dynamics of fluid surface oscillations and the properties of a surfactant monolayer in the vicinity of the phase transition from a gas-like distribution to a liquid-like assembly (the so-called gas鈥揕E transition). Important charge effects are also considered. The basic assumptions of the model (cooperative adsorption of the surfactant at the air鈥搘ater interface and coupling between the shape of the deformed surface and the local surfactant concentration) have been fully confirmed by extensive coarse-grained molecular dynamics simulations on model systems.