The Pull-Off Force and the Work of Adhesion: New Challenges at the Nanoscale

Moore, Nathan W.; Houston, Jack E.

doi:10.1163/016942410x508325

Cited by 22 publications

(27 citation statements)

References 44 publications

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“…The forces on approach at the lowest biases (<3 V, Figure 2) are characteristically similar to those observed earlier with IFM involving capillary condensation between other insulating surfaces, including NaCl, diamond, poly(vinyl acetate) and carboxylated self-assembled monolayers (SAMs), 10,11,41,42 supporting that the transition at D* stemmed from capillary condensation and not from electrical discharge. Both the discontinuity in the force at D* and the linear scaling of the force with separation for D < D* are established features of capillary nanobridges at constant vapor pressure (for reviews of surface forces, see refs 3, 8, 22, and 43).…”

Section: ' Methods and Materialssupporting

confidence: 83%

“…Because force cannot be measured during the last 1À2 nm of separation, owing to the elastic instability of the surfaces themselves under van der Waals attraction, this approach may underestimate D C by <1À2 nm. 10 Although the applied fields of up to ∼10 9 V/m are much higher than the field required for dielectric breakdown of air (∼3 Â 10 6 V/m), the transition at D* is distinct from what has been observed during discharging of other insulating surfaces. The latter has been characterized as a series of force excursions that lessen the magnitude of force as potential is relieved.…”

Section: ' Methods and Materialsmentioning

confidence: 93%

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Adhesion Hysteresis from Interdependent Capillary and Electrostatic Forces

Moore

2011

Langmuir

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Adhesion hysteresis commonly occurs at the nanoscale in humid atmospheres, yet mechanisms are not entirely understood. Here, the adhesion forces between silicon (111) oxide surfaces and tungsten oxide probes have been examined using interfacial force microscopy. The results show that the adhesion forces during surface approach and separation differ not only in magnitude but also in mechanism, arising mainly from capillary and electrostatic forces, respectively. Surface contact leads to a transient intersurface potential on dewetting. This mechanism of adhesion hysteresis differs in not relying singly on hysteretic wetting. Furthermore, by biasing the surfaces, nonadditivity is demonstrated between the capillary and electrostatic forces at the onset of condensation. These results hold important implications on the interpretation of force in nanoprobe geometries in humid atmospheres.

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Section: ' Methods and Materialssupporting

confidence: 83%

Section: ' Methods and Materialsmentioning

confidence: 93%

Adhesion Hysteresis from Interdependent Capillary and Electrostatic Forces

Moore

2011

Langmuir

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“…In another study, the IFM was used to study a silicon/silicon interface under a variety of conditions. [ 35 ] Results varied widely between different tests, even for similar conditions. For instance, for self-mated silicon interfaces (with a native oxide) in air, work of adhesion values were reported to range from [ 32 ] 0.040 J m −2 up to [ 12 ] 0.83 J m −2 -likely due to differences in roughness and surface preparation.…”

Section: Introductionmentioning

confidence: 97%

“…This quantity is the correct one for use in continuum contact models [4][5][6]8,27,28 ] as well as in roughness models. [ 26,29,30 ] The investigations in this second category have employed the atomic force microscope (AFM), [ 8,12,[31][32][33][34] the related interfacial force microscope (IFM), [ 35 ] and the surface forces apparatus (SFA) [ 36,37 ] to conduct adhesion tests with high-force resolution using a single-asperity contact, typically on the nanometer length scale. Since these are not fl at surfaces, a value for work of adhesion requires using a contact mechanics model to fi t the data.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the Length and Strength of Adhesive Interactions in a Nanoscale Silicon–Diamond Interface

Jacobs¹,

Lefever²,

Carpick³

2015

Adv Materials Inter

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the interaction (characterized by the range of adhesion z 0 ).The intrinsic work of adhesion W adh is the energy per unit area required to separate two planar surfaces from equilibrium contact to infi nite separation. In terms of surface energy (γ i of surface i ) and interfacial energy (γ ij between surfaces i and j ), the work of adhesion is calculated as follows:In accordance with prior literature on adhesion and roughness, [ 9 ] the intrinsic work of adhesion W adh,int is defi ned as the work of adhesion between two perfectly fl at, planar surfaces. While W adh,int is a continuum concept, it can be robustly mapped onto an atomistic description of two atomically fl at, single-crystal surfaces in contact. The effective work of adhesion, W adh,eff , is defi ned as the work of adhesion for the same material pair and the same global geometry (planar), but with the addition of local surface roughness on one or both surfaces. The distinction between W adh,int and W adh,eff is shown schematically in Figure 1 . The W adh,int is determined by the identity of the materials in contact, and the environment, whereas W adh,eff is a function of W adh,int and the local surface topography. For hard, non-conforming materials, W adh,eff is typically much smaller than W adh,int . The primary reason for this is that the roughness increases the effective separation between the two materials, and therefore signifi cantly increases γ ij between the materials as they can no longer make intimate contact. Roughness can also increase the surface energies γ i and γ j , but this effect is typically overwhelmed by the change in γ ij . This distinction is drawn because many experimental techniques exist to measure W adh,eff (for example, using microfabricated beam tests [ 10 ] ), but generally applicable techniques to deduce from this the W adh,int are not well established.Physically, z 0 describes the equilibrium separation distance between perfectly fl at surfaces, i.e., the separation distance at which their interaction force is zero. However, in many mathematical descriptions of adhesion (for instance, refs. [ 5,7,8,11 ] ) z 0 also scales the distance over which adhesion acts for a particular material. Therefore, the parameter z 0 is referred to in this paper as the "range of adhesion," (in accordance with Greenwood, [ 5 ] who calls it the "range of action of the surface forces").The adhesive interactions between nanoscale silicon atomic force microscope (AFM) probes and a diamond substrate are characterized using in situ adhesion tests inside of a transmission electron microscope (TEM). In particular, measurements are presented both for the strength of the adhesion acting between the two materials (characterized by the intrinsic work of adhesion W adh,int ) and for the length scale of the interaction (described by the range of adhesion z 0 ). These values are calculated using a novel analysis technique that requires measurement of the AFM probe geometry, the adhesive force, and the position where the snap-in instability occurs. Values ...

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“…Several authors have used IFM to study the range of formation, the interaction force, and the viscoelastic properties of nanomenisci [8,10,29,107]. These studies have shown unprecedented detail in the force that evolves between a probe and nearby surface as vapor condenses into liquid and is displaced beneath the approaching probe.…”

Section: Hydration Repulsion Inside a Nanoconfined Meniscusmentioning

confidence: 99%

Studies of the viscoelastic properties of water confined between surfaces of specified chemical nature.

Houston¹,

Grest²,

Moore³

et al. 2010

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This report summarizes the work completed under the Laboratory Directed Research and Development (LDRD) project 10-0973 of the same title. Understanding the molecular origin of the no-slip boundary condition remains vitally important for understanding molecular transport in biological, environmental and energy-related processes, with broad technological implications. Moreover, the viscoelastic properties of fluids in nanoconfinement or near surfaces are not well-understood. We have critically reviewed progress in this area, evaluated key experimental and theoretical methods, and made unique and important discoveries addressing these and related scientific questions. Thematically, the discoveries include insight into the orientation of water molecules on metal surfaces, the premelting of ice, the nucleation of water and alcohol vapors between surface asperities and the lubricity of these molecules when confined inside nanopores, the influence of water nucleation on adhesion to salts and silicates, and the growth and superplasticity of NaCl nanowires.

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The Pull-Off Force and the Work of Adhesion: New Challenges at the Nanoscale

Cited by 22 publications

References 44 publications

Adhesion Hysteresis from Interdependent Capillary and Electrostatic Forces

Adhesion Hysteresis from Interdependent Capillary and Electrostatic Forces

Measurement of the Length and Strength of Adhesive Interactions in a Nanoscale Silicon–Diamond Interface

Studies of the viscoelastic properties of water confined between surfaces of specified chemical nature.

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