Capillary Forces in Nanoparticle Adhesion: A Review of AFM Methods

Harrison, Aaron J.; Corti, David S.; Beaudoin, Stephen P.

doi:10.1080/02726351.2015.1045641

Cited by 60 publications

(52 citation statements)

References 67 publications

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“…The AFM force-curves are conducted at a rate of 2 kHz allowing a contact of both surfaces in the order of the milliseconds [38–39] at ambient temperature (20 °C) and relative humidity around 35 ± 5%. A pure equilibrium state ensuring the constant formation of the water meniscus might be difficult to reach all the time as these values are at the formation limit, as discussed by Haugstad et al [39]; however, it is still possible and it can explain the large spread of adhesion values obtained for –NH 2 and –SH coated NPs.…”

Section: Resultsmentioning

confidence: 99%

“…When plotted on a logarithmic scale, adhesion values for hydrophobic NPs can be well approximated by linear fit corresponding to an exponential decay of the adhesion with NPs size, which is known as size effect [38]. This slope is slightly higher for the –CH 3 coated NPs, indicating a stronger decrease of the input molecular interactions with the NPs size than for partially hydrophobic NPs as one could expect for the lowest nanoparticle coating adhesion.…”

Section: Resultsmentioning

confidence: 99%

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Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Oras

Vlassov

Berholts

et al. 2018

Beilstein J. Nanotechnol.

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Adhesion forces between functionalized gold colloidal nanoparticles (Au NPs) and scanning probe microscope silicon tips were experimentally investigated by atomic force microscopy (AFM) equipped with PeakForce QNM (Quantitative Nanoscale Mechanics) module. Au NPs were synthesized by a seed-mediated process and then functionalized with thiols containing different functional groups: amino, hydroxy, methoxy, carboxy, methyl, and thiol. Adhesion measurements showed strong differences between NPs and silicon tip depending on the nature of the tail functional group. The dependence of the adhesion on ligand density for different thiols with identical functional tail-group was also demonstrated. The calculated contribution of the van der Waals (vdW) forces between particles was in good agreement with experimentally measured adhesive values. In addition, the adhesion forces were evaluated between flat Au films functionalized with the same molecular components and silicon tips to exclude the effect of particle shape on the adhesion values. Although adhesion values on flat substrates were higher than on their nanoparticle counterparts, the dependance on functional groups remained the same.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Oras

Vlassov

Berholts

et al. 2018

Beilstein J. Nanotechnol.

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“…Capillary force has been shown to vary with RH. It can exhibit monotonic increase or decrease, peak at certain RHs, show step-wise increases, or be independent of RH; the variations depend on particle properties such diameter, shape, surface hydrophilicity, and roughness (Butt and Kappl 2009;Harrison et al 2015).…”

Section: Discussionmentioning

confidence: 99%

Deagglomeration testing of airborne nanoparticle agglomerates: Stability analysis under varied aerodynamic shear and relative humidity conditions

Ding

Stahlmecke

Kaminski

et al. 2016

Aerosol Science and Technology

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2016) Deagglomeration testing of airborne nanoparticle agglomerates: Stability analysis under varied aerodynamic shear and relative humidity conditions, ABSTRACTOccupational exposure to nanomaterial aerosols poses potential health risks to workers at nanotechnology workplaces. Understanding the mechanical stability of airborne nanoparticle agglomerates under varied mechanical forces and environmental conditions is important for estimating their emission potential and the released particle size distributions, which in consequence alters their transport and human uptake probability. In this study, two aerosolization and deagglomeration systems were used to investigate the potential for deagglomeration of nanopowder aerosols with different surface hydrophilicity under a range of shear forces and relative humidity conditions. Critical orifices were employed to subject airborne agglomerates to the shear forces induced by a pressure drop. Increasing applied pressure drop was found to be associated with decreased mean particle size and increased particle number concentrations. Rising humidity decreased the deagglomeration tendency as expressed by larger modal particle sizes and lower number concentrations compared to dry conditions. Hydrophilic aerosols exhibited higher sensitivities to changes in humidity than hydrophobic particles. However, the test systems themselves also differed in generated particle number concentrations and size distributions, which in turn altered the responses of created aerosols to humidity changes. The results of the present study clearly demonstrate that (a) humidity control is essential for dustiness and deagglomeration testing, (b) that (industrial) deagglomeration, for example, for preparation of aerosol suspensions, can be manipulated by subjecting airborne particles to external energies, and (c) that the humidity of workplace air may be relevant when assessing occupational exposure to nanomaterial aerosols. EDITOR Nicole Riemer CONTACT Michael Riediker Michael.Riediker@alumni.ethz.ch Institute for Work and Health (IST), Universities of Lausanne and Geneva, Route de la Corniche 2, Epalinges CH-1066, Switzerland. Color versions of one or more figures in the article can be found online at www.tandfonline.com/uast.

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“…If a solid surface is hydrophilic, strong interactions between the solid surface and water molecules may result in the formation of a strongly H-bonded water layer, also denoted as ordered water, solid-like water, ice-like water, or quasi-ice, in the adsorbed layer [10]. Water condensation around nanoasperity contacts varies with not only the intrinsic properties of the contacting surfaces (e.g., atomic structure, dangling bond, wettability, chemical activity, and surface roughness), but also the working conditions (e.g., temperature, humidity, sliding velocity, and atmosphere) ( Figure 1) [14][15][16]. Apart from the amount of adsorbed water, the structure of the adsorbed water layer also plays a significant role in interfacial forces at the nanoasperity contact, especially under ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

“…A typical technique to quantify interfacial adhesion involves measurement of the pull-off force using AFM. Extensive experiments carried out in humid air show that F a is dominated by the capillary interaction, which varies with RH as well as the surface wettability or surface chemistry [14,15]. The RH-dependent F c plays an important role in adhesion behaviors.…”

Section: Brief Introduction Of Water Adsorption-dependent Adhesion Fomentioning

confidence: 99%

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Xiao

Shi

et al. 2019

Colloids and Interfaces

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Most inorganic material surfaces exposed to ambient air can adsorb water, and hydrogen bonding interactions among adsorbed water molecules vary depending on, not only intrinsic properties of material surfaces, but also extrinsic working conditions. When dimensions of solid objects shrink to micro- and nano-scales, the ratio of surface area to volume increases greatly and the contribution of water condensation on interfacial forces, such as adhesion (Fa) and friction (Ft), becomes significant. This paper reviews the structural evolution of the adsorbed water layer on solid surfaces and its effect on Fa and Ft at nanoasperity contact for sphere-on-flat geometry. The details of the underlying mechanisms governing water adsorption behaviors vary depending on the atomic structure of the substrate, surface hydrophilicity and atmospheric conditions. The solid surfaces reviewed in this paper include metal/metallic oxides, silicon/silicon oxides, fluorides, and two-dimensional materials. The mechanism by which water condensation influences Fa is discussed based on the competition among capillary force, van der Waals force and the rupture force of solid-like water bridge. The condensed meniscus and the molecular configuration of the water bridge are influenced by surface roughness, surface hydrophilicity, temperature, sliding velocity, which in turn affect the kinetics of water condensation and interfacial Ft. Taking the effects of the thickness and structure of adsorbed water into account is important to obtain a full understanding of the interfacial forces at nanoasperity contact under ambient conditions.

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Capillary Forces in Nanoparticle Adhesion: A Review of AFM Methods

Cited by 60 publications

References 67 publications

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

Deagglomeration testing of airborne nanoparticle agglomerates: Stability analysis under varied aerodynamic shear and relative humidity conditions

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

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