Argyri Smaragda-Maria, Almeida Maëva, Cousin Fabrice, Evenäs Lars, Fameau Anne-Laure, Le Coeur Clémence, Bordes Romain
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden; Laboratoire Léon Brillouin, Université Paris-Saclay, CEA-CNRS UMR 12 CEA Saclay, 91191 Gif sur Yvette, France.
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden; CNRS, ICMPE, UMR 7182, 2 Rue Henri Dunant, Université Paris Est Creteil, 94320 Thiais, France; Laboratoire Léon Brillouin, Université Paris-Saclay, CEA-CNRS UMR 12 CEA Saclay, 91191 Gif sur Yvette, France.
J Colloid Interface Sci. 2025 Jan 15;678(Pt C):1181-1191. doi: 10.1016/j.jcis.2024.09.123. Epub 2024 Sep 14.
Acoustic levitation is a suitable approach for studying processes occurring at the gas-liquid interfaces, as it allows its investigation in a contact-free manner while providing control over the gas phase. Here, we hypothesize that phase transitions induced by a CO rich atmosphere can be examined, at different length scales, in a contact-free manner.
A system consisting of 12-hydroxysteric acid (HSA) soaps mixed with different ratios of monoethanolamine (MEA) and choline hydroxide, was prepared. Microliter droplets of the samples were acoustically levitated and monitored with a camera, while exposed to CO to modify the pH through diffusion at the air-liquid interface and inside the droplet. The phase transition and water mobility in the levitated droplets were evaluated through X-ray scattering (SAXS/WAXS) and magnetic resonance studies, in real-time. Finally, the droplets were collected and examined under the microscope.
The introduction of CO gas induced a phase transition from micelles to multi-lamellar tubes, resulting in a gel-like behavior both in the bulk and at the interface. The high stability of the acoustic levitator allowed the investigation of this dynamic phenomenon, in real-time, in a contact-free environment. This study showcases the suitability of acoustic levitation as a tool to investigate complex chemical processes at interfaces.
声悬浮是研究气液界面发生过程的一种合适方法，因为它能以非接触方式进行研究，同时可对气相进行控制。在此，我们假设由富含一氧化碳的气氛诱导的相变能够以非接触方式在不同长度尺度下进行研究。
制备了一个由12 - 羟基硬脂酸（HSA）肥皂与不同比例的单乙醇胺（MEA）和氢氧化胆碱混合而成的体系。将微升体积的样品液滴进行声悬浮，并用相机进行监测，同时使其暴露于一氧化碳中，通过在气液界面和液滴内部的扩散来改变pH值。通过X射线散射（小角X射线散射/广角X射线散射）和磁共振研究实时评估悬浮液滴中的相变和水的流动性。最后，收集液滴并在显微镜下进行检查。
引入一氧化碳气体导致从胶束到多层管的相变，在本体和界面处均产生凝胶状行为。声悬浮器的高稳定性使得能够在非接触环境中实时研究这种动态现象。本研究展示了声悬浮作为研究界面复杂化学过程工具的适用性。
