The Department of Chemical & Biomolecular Engineering, The Particulate Fluids Processing Centre, The University of Melbourne, Parkville, Victoria 3010, Australia.
Langmuir. 2012 Dec 18;28(50):17230-7. doi: 10.1021/la304351a. Epub 2012 Dec 6.
Reversibly switchable surfactants are increasingly important for controlling foam stability in many industrial applications because they can be recycled as foaming and antifoaming agents. Novel stimuli responsive peptide surfactants have been previously studied to classify the molecular conformation at the air-water interface before and after switching. In this study, Atomic Force Microscopy (AFM) was used to correlate the peptide conformation to directly measured changes in colloidal interaction forces between immobilized air bubbles before and after switching. The surface tension values extracted from the AFM force measurements were compared to macroscopic pendant drop measurements to help elucidate the importance of desorption in the switching mechanisms for some of the peptides. Results were compared to previous studies of macroscopic foam-column stability using these peptides. Differences in foam stability and the AFM force measurements were apparent, highlighting variations in directly measured equilibrium colloidal interactions to macroscopic bulk behavior. These results help elucidate the connection between the switching mechanism of novel stimuli responsive peptide surfactants and their effect on colloidal scale interactions between bubbles.
可反复切换的表面活性剂在许多工业应用中对于控制泡沫稳定性变得越来越重要，因为它们可以作为发泡剂和消泡剂回收利用。先前已经研究了新型刺激响应肽表面活性剂，以在切换前后对气-水界面处的分子构象进行分类。在这项研究中，原子力显微镜（AFM）用于将肽构象与直接测量的固定气泡之间胶体相互作用力在切换前后的变化相关联。从 AFM 力测量中提取的表面张力值与宏观吊片测量进行了比较，以帮助阐明在某些肽的切换机制中解吸的重要性。结果与之前使用这些肽的宏观泡沫柱稳定性的研究进行了比较。泡沫稳定性和 AFM 力测量的差异很明显，突出了直接测量的平衡胶体相互作用与宏观整体行为之间的差异。这些结果有助于阐明新型刺激响应肽表面活性剂的切换机制与其对气泡之间胶体尺度相互作用的影响之间的联系。
