Quantitative Analysis of Fluid Interface–Atomic Force Microscopy

Aston, D. Eric; Berg, John C.

doi:10.1006/jcis.2000.7351

Cited by 86 publications

(123 citation statements)

References 31 publications

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“…For systems involving a deformable interface, zero separation distance becomes more difficult to determine due to the coupling effect of interfacial deformation and cantilever bending upon applied force. [25][26][27][28][29][30] Adsorbed interfacial species can greatly influence interaction forces and also govern the degree of droplet deformation under applied load, with the latter greatly influenced by interfacial rigidity. 31 In the absence of hydrodynamic effects, droplet deformation results from the interaction forces exceeding the Laplace pressure.…”

Section: Introductionmentioning

confidence: 99%

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

et al. 2017

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Atomic force microscopy (AFM) is frequently used to elucidate complex interactions in emulsion systems. However, comparing results obtained with "model" planar surfaces to curved emulsion interfaces often proves unreliable, since droplet curvature can affect adsorption and arrangement of surface-active species, while droplet deformation affects the net interaction force.In the current study, AFM was utilized to study the interactions between a colloidal probe and water droplet. Force magnitude and water droplet deformation were measured in asphaltene and bitumen solutions of different concentrations at various droplet aging times. Interfacial stiffening and an increase in particle-droplet adhesion force were observed upon droplet aging in bitumen solution. As reported in our previous study (Kuznicki, N. P.; Harbottle, D.; Masliyah, J.; Xu, Z. Dynamic Interactions between a Silica Sphere and Deformable Interfaces in Organic SolventsStudied by Atomic Force Microscopy. Langmuir 2016, 32 (38), 9797−9806), a viscoelasticity parameter should be included in the high force Stokes-Reynolds-Young-Laplace (SRYL) equations to account for the interfacial stiffening and non-Laplacian response of the water droplet at longer aging times. However, following the addition of a biodegradable demulsifier, ethyl cellulose (EC), an immediate reduction in both the particle-droplet adhesion force and the rigidity of the water droplet occurred. Following EC addition, the interface reverted back to a 2 Laplacian response and droplet deformation was once again accurately predicted by the classical SRYL model. These changes in both droplet deformation and particle-droplet adhesion, tracked by AFM, imply a rapid asphaltene/bitumen film displacement by EC molecules. The colloidal probe technique provides a convenient way to quantify forces at deformable oil/water interfaces and characterize the in-situ effectiveness of competing surface active species.

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Section: Introductionmentioning

confidence: 99%

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

et al. 2017

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“…During the past few years there has been growing experimental [1,2,3,4,5,6,7,8,9,10,11] and theoretical [12,13,14,15,16,17,18,19,20,21,22], interest in systems where deformable surfaces interact with colloidal particles in liquids. These systems are important as they commonly appear in both nature and in technical situations.…”

Section: Introductionmentioning

confidence: 99%

Fluid drop shape determination by the Rayleigh--Ritz minimization method

Cortat¹,

Miklavcic²

2007

ANZIAMJ

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The Rayleigh-Ritz (rr) method is well known as a means of minimizing energy functionals. Despite this, the technique most often employed in practice for minimizing a functional is the numerical solution of the Euler-Lagrange (el) equations derived from the energy functional by variational minimization. In this article we employ the rr method specifically to determine the equilibrium shape of a fluid drop interface deformed by externally applied surface stresses and compare the results with numerical solution of the el equations. We give examples of conditions where the rr method is superior in terms of simplicity and accuracy to the numerical el solution, as well as conditions under which the method is less reliable.

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“…These later techniques include total internal reflection microscopy, a modified surface forces apparatus, 2,3 alignment of droplets in magnetic fields 4,5 and atomic force microscopy (AFM). [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] All of these measurements are motivated by the study of how the structure of the molecules at liquid interfaces mediates the interaction forces between liquid-liquid or liquid-vapor interfaces. Understanding the interaction forces between liquid interfaces leads to insight into the properties of complex fluids commonly encountered in industrial applications.…”

Section: Introductionmentioning

confidence: 99%

“…The data analysis methods for rigid systems are not applicable to deformable surfaces. 10,11,14 In the analysis for rigid systems, measurement of force versus motion of the piezo distance actuator is converted to force versus intersurface separation. For this to be accomplished in deformable systems, one must separate the effects of interface deformation from changes in the interaction forces.…”

Section: Introductionmentioning

confidence: 99%

“…A number of theoretical studies have examined this type of measurement and proposed several methods to analyze this type of data. [10][11][12]14,16,19,20,28 All the approaches involve modeling the deformation of the interface via the Young-Laplace equation where the drop shape is perturbed by the presence of the rigid probe. The drop size employed in the AFM experiments is typically below the capillary length of the system, thus surface tension and surface forces govern the interface shape where the effects of gravity are negligible.…”

Section: Introductionmentioning

confidence: 99%

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Interaction forces between oil–water particle interfaces—Non-DLVO forces

et al. 2005

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The interaction force between a rigid silica sphere and a butyl or octyl acetate droplet was measured in an aqueous environment using atomic force microscopy (AFM). The force measurements were performed without added stabilizers and the observed force behavior was found to be dependent on the type of inorganic electrolyte present, where the interfacial tension was constant over the electrolyte concentration range used. Force measurements in the presence of sodium nitrate showed repulsion at all concentrations. Force measurements in the presence of calcium nitrate or sodium perchlorate exhibited an initial repulsion followed by an attraction resulting in a mechanical instability in the AFM cantilever, termed jump-in. The force behavior observed was independent of the water solubility of the organic liquid, in that the same force-distance characteristics were obtained for slightly water soluble butyl acetate and the water sparingly soluble octyl acetate droplets. Modeling of the drop profile during particle-droplet interactions for this type of AFM measurement showed that the force-distance data for the sodium nitrate system obeys typical DLVO interactions. The disagreement between the DLVO predictions for the sodium perchlorate and calcium nitrate systems is attributed to a specific ion effect at the liquid-liquid interface, which gives rise to an attraction force that is greater than the electrostatic double layer repulsion over the length scale of 5 to 10 nm.

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Quantitative Analysis of Fluid Interface–Atomic Force Microscopy

Cited by 86 publications

References 31 publications

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

Fluid drop shape determination by the Rayleigh--Ritz minimization method

Interaction forces between oil–water particle interfaces—Non-DLVO forces

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