The Origin of the “Snap‐In” in the Force Curve between AFM Probe and the Water/Gas Interface of Nanobubbles

Song, Yang; Zhao, Binyu; Zhang, Lijuan; Lü, Junhong; Wang, Shuo; Dong, Yaming; Hu, Jun

doi:10.1002/cphc.201301081

Cited by 19 publications

(11 citation statements)

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“…In comparison, for the tip-nanostructure regime interaction, jump-in was observed at a much larger separation, and the force–separation curve before jump-out showed much smaller slope, implying that the nanostructure regimes experienced large deformations during the interaction process. Interestingly, the force curve of the tip-nanostructure interaction is similar to that between a tip and a nanobubble reported previously. ,− Therefore, these soft nanostructure regimes on the hydrophobic PS surface (Figure A,B) are believed to be the INBs.…”

Section: Resultssupporting

confidence: 82%

Probing Interactions between Air Bubble and Hydrophobic Polymer Surface: Impact of Solution Salinity and Interfacial Nanobubbles

et al. 2016

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The interactions between air bubbles and hydrophobic polymer surfaces in aqueous media play important roles in many industrial and engineering processes. In this work, the interaction forces between air bubble and a model hydrophobic polymer-polystyrene (PS) in NaCl solutions (1 mM to 1000 mM) were directly measured using a bubble probe atomic force microscope (AFM) technique, and the measured forces were analyzed by a theoretical model based on Reynolds lubrication theory and augmented Young-Laplace equation including the influence of disjoining pressure. It was found that the theoretical analysis, by assuming that the PS surface was a pristine and bare polymer surface in aqueous solutions, could not fully agree with the experimental force measurements at intermedium salinity condition (i.e., 100 mM NaCl), and the discrepancy could not be described by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory even including the effects of non-DLVO interactions such as hydrophobic interaction. Atomic force microscope (AFM) imaging demonstrated that the above discrepancy was caused by the presence of interfacial nanobubbles (INBs) on the hydrophobic PS surface. The solution salinity was found to significantly affect the size and surface coverage of INBs on the PS surface, thereby influencing the surface forces. At high NaCl concentration (e.g., 500 and 1000 mM), the INB formation (and its impact on the surface interactions) and electric double layer repulsion were highly suppressed, and the bubble-PS attachment was observed attributing to their hydrophobic attraction with a decay length of ∼0.75 ± 0.05 nm. The results agree with our previous surface force measurements between two PS surfaces using a surface forces apparatus. This work provides useful insights into the interaction mechanism between air bubbles and hydrophobic polymer surfaces, as well as the influence of solution salinity and interfacial nanobubbles on the bubble-polymer interaction.

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Section: Resultssupporting

confidence: 82%

Probing Interactions between Air Bubble and Hydrophobic Polymer Surface: Impact of Solution Salinity and Interfacial Nanobubbles

et al. 2016

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“…2a,b ). This difference occurred because the AFM tip usually penetrates into fluid structures to a certain depth that depends on the hydrophobicity of the tip 30 , in order to achieve a positive pre-set peak force due to the capillary force between the tip and the fluid structure 29 . When the fluid structure is too thin, the tip traces the profile of the underlying stiff structure (the substrate, in this case).…”

Section: Resultsmentioning

confidence: 99%

Nucleation processes of nanobubbles at a solid/water interface

Fang

Yang

et al. 2016

Sci Rep

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Experimental investigations of hydrophobic/water interfaces often return controversial results, possibly due to the unknown role of gas accumulation at the interfaces. Here, during advanced atomic force microscopy of the initial evolution of gas-containing structures at a highly ordered pyrolytic graphite/water interface, a fluid phase first appeared as a circular wetting layer ~0.3 nm in thickness and was later transformed into a cap-shaped nanostructure (an interfacial nanobubble). Two-dimensional ordered domains were nucleated and grew over time outside or at the perimeter of the fluid regions, eventually confining growth of the fluid regions to the vertical direction. We determined that interfacial nanobubbles and fluid layers have very similar mechanical properties, suggesting low interfacial tension with water and a liquid-like nature, explaining their high stability and their roles in boundary slip and bubble nucleation. These ordered domains may be the interfacial hydrophilic gas hydrates and/or the long-sought chemical surface heterogeneities responsible for contact line pinning and contact angle hysteresis. The gradual nucleation and growth of hydrophilic ordered domains renders the original homogeneous hydrophobic/water interface more heterogeneous over time, which would have great consequence for interfacial properties that affect diverse phenomena, including interactions in water, chemical reactions, and the self-assembly and function of biological molecules.

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“…In some studies, it has been pointed out that the long-range attractive force between the macrobubbles and particles is mainly due to the charge effect and the hydrophobic force. However, Song et al , found that the influence of the charge effect was very small on the interaction between the probe and the nanobubbles, and hydrophobicity was the main factor for the generation of attractive force. Therefore, one of the reasons that the attraction and adhesion between the tip and the INBs improved is the increase of the probe hydrophobicity.…”

Section: Resultsmentioning

confidence: 99%

Study of Interactions between Interfacial Nanobubbles and Probes of Different Hydrophobicities

et al. 2020

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In this study, hydrophilic, medium hydrophobic, and strong hydrophobic probes are obtained via treatment with plasma and octadecyl trichlorosilane. The interaction between the probes and interfacial nanobubbles (INBs) is examined using atomic force microscopy. The results show that a hydrophilic probe can scan the true shape of the INBs, and the distance between the first inflection point and the zero point of the approach force curve is equal to the vertical height of the nanobubble. The medium hydrophobic probe caused severe deformation of INB morphologies in the horizontal direction during scanning; nevertheless, the complete shape of the INB is obtained using this probe by lowering the scanning parameters. However, the characteristic of the approach force curve proves that the size of the nanobubbles is underestimated. The strong hydrophobic probe deforms INB morphologies severely, whose size cannot be obtained. The maximum attractive force in the approach force curve and the adhesive force in the retract force curve obtained using the strong hydrophobic probe are approximately 6 and 12 nN, respectively, which are both higher than those of the hydrophilic and medium hydrophobic probes. It is reasoned that the liquid film is maintained between the hydrophilic probe and the INBs, the medium hydrophobic probe pierces the INBs slightly, while the strong hydrophobic probe punctures the liquid film and demonstrates a pinning effect.

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The Origin of the “Snap‐In” in the Force Curve between AFM Probe and the Water/Gas Interface of Nanobubbles

Cited by 19 publications

References 50 publications

Probing Interactions between Air Bubble and Hydrophobic Polymer Surface: Impact of Solution Salinity and Interfacial Nanobubbles

Probing Interactions between Air Bubble and Hydrophobic Polymer Surface: Impact of Solution Salinity and Interfacial Nanobubbles

Nucleation processes of nanobubbles at a solid/water interface

Study of Interactions between Interfacial Nanobubbles and Probes of Different Hydrophobicities

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