Particle detachment from fluid interfaces: theory vs. experiments

Anachkov, Svetoslav E.; Lesov, Ivan; Zanini, Michele; Kralchevsky, Peter A.; Denkov, Nikolai D.; Isa, Lucio

doi:10.1039/c6sm01716a

Cited by 53 publications

(66 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We remark that the range of surface heterogeneities for our particles are on a different scale than surface defects previously studied28, for which thermally activated contact line motion over the defects has been observed9. In fact, the energy barriers associated to the contact line moving over single asperities on our rough particles can be directly calculated29 and are at least of the order of 10 3 k B T (see Supplementary Note 8). This implies that our rough particles are strongly trapped in metastable states and even the energy introduced during an emulsification process is not sufficient to induce a relaxation of the particles' position relative to the interface.…”

Section: Discussionmentioning

confidence: 77%

Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

et al. 2017

Self Cite

View full text Add to dashboard Cite

Surface heterogeneities, including roughness, significantly affect the adsorption, motion and interactions of particles at fluid interfaces. However, a systematic experimental study, linking surface roughness to particle wettability at a microscopic level, is currently missing. Here we synthesize a library of all-silica microparticles with uniform surface chemistry, but tuneable surface roughness and study their spontaneous adsorption at oil–water interfaces. We demonstrate that surface roughness strongly pins the particles' contact lines and arrests their adsorption in long-lived metastable positions, and we directly measure the roughness-induced interface deformations around isolated particles. Pinning imparts tremendous contact angle hysteresis, which can practically invert the particle wettability for sufficient roughness, irrespective of their chemical nature. As a unique consequence, the same rough particles stabilize both water-in-oil and oil-in-water emulsions depending on the phase they are initially dispersed in. These results both shed light on fundamental phenomena concerning particle adsorption at fluid interfaces and indicate future design rules for particle-based emulsifiers.

show abstract

Section: Discussionmentioning

confidence: 77%

Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…The theoretical capillary force (equations ) has been shown to agree well with experimental measurements, albeit the theoretical calculations have been mostly restricted to spheres. Vertical capillary forces on spherical particles have been measured with tensiometry [ Zhang et al ., ; Shang et al ., ] and AFM [ Preuss and Butt , , ; Butt et al ., ; Gillies et al ., ; Anachkov et al ., ; Knüpfer et al ., ]. These types of measurements provide so‐called force‐distance curves, i.e., the force as a function of the position of the air‐water interface, often expressed as the distance between the flat air‐water interface and the particle.…”

Section: Interactions Of Colloids and Air‐water Interfacesmentioning

confidence: 99%

Role of air‐water interfaces in colloid transport in porous media: A review

Flury

Aramrak

2017

Water Resources Research

103

View full text Add to dashboard Cite

Air‐water interfaces play an important role in unsaturated porous media, giving rise to phenomena like capillarity. Less recognized and understood are interactions of colloids with the air‐water interface in porous media and the implications of these interactions for fate and transport of colloids. In this review, we discuss how colloids, both suspended in the aqueous phase and attached at pore walls, interact with air‐water interfaces in porous media. We discuss the theory of colloid/air‐water interface interactions, based on the different forces acting between colloids and the air‐water interface (DLVO, hydrophobic, capillary forces) and based on thermodynamic considerations (Gibbs free energy). Subsurface colloids are usually electrostatically repelled from the air‐water interface because most subsurface colloids and the air‐water are negatively charged. However, hydrophobic interactions can lead to attraction to the air‐water interface. When colloids are at the air‐water interface, capillary forces are usually dominant over other forces. Moving air‐water interfaces are effective in mobilizing and transporting colloids from surfaces. Thermodynamic considerations show that, for a colloid, the air‐water interface is the favored state as compared with the suspension phase, except for hydrophilic colloids in the nanometer size range. Experimental evidence indicates that colloid mobilization in soils often occurs through macropores, although matrix transport is also prevalent in absence of macropores. Moving air‐water interfaces, e.g., occurring during infiltration, imbibition, or drainage, have been shown to scour colloids from surfaces and translocate colloids. Colloids can also be pinned to surfaces by thin water films and capillary menisci at the air‐water‐solid interface line, causing colloid retention and immobilization. Air‐water interfaces thus can both mobilize or immobilize colloids in porous media, depending on hydrodynamics and colloid and surface chemistry.

show abstract

“…[21]. Because of its practical importance, the detachment of a particle from a planar liquid surface has been studied for a long time [19,[22][23][24][25][26][27][28][29][30][31][32]. The quasistatic removal of a sphere from a liquid surface has a strong connection with the meniscus on the outside of a cylinder in a liquid bath, which is governed by the Young-Laplace equation.…”

Section: Introductionmentioning

confidence: 99%

“…Pitois and Chateau studied the work of detachment of removing a small particle from an interface both experimentally and analytically using a theory based on the Derjaguin-James formula [27,28]. Anachkov et al recently refined Pitois and Chateau's theory by correcting the critical central angle at which a capillary bridge ruptures and compared the theory with experimental data collected with a colloidal-probe atomic force microscope (AFM) [30].…”

Section: Introductionmentioning

confidence: 99%

Capillary forces on a small particle at a liquid-vapor interface: Theory and simulation

Yan

Cheng

2018

Phys. Rev. E

View full text Add to dashboard Cite

We study the meniscus on the outside of a small spherical particle with radius R at a liquid-vapor interface. The liquid is confined in a cylindrical container with a finite radius L and has a contact angle π/2 at the container surface. The center of the particle is placed at various heights along the central axis of the container. By varying L, we are able to systematically study the crossover of the meniscus from nanometer to macroscopic scales. The meniscus rise or depression on the particle is found to grow as ln(2L/R) when R ≪ L ≪ κ −1 with κ −1 being the capillary length and saturate to a value predicted by the Derjaguin-James formula when R ≪ κ −1 ≪ L. The capillary force on the particle exhibits a linear dependence on the particle's displacement from its equilibrium position at the interface when the displacement is small. The associated spring constant is found to be 2πγ ln −1 (2L/R) for L ≪ κ −1 and saturates to 2πγ ln −1 (3.7κ −1 /R) for L ≫ κ −1 . At nanometer scales, we perform molecular dynamics simulations of the described geometry and the results agree well with the predictions of the macroscopic theory of capillarity. At micrometer to macroscopic scales, comparison to experiments by Anachkov et al. [Soft Matter 12, 7632 (2016)] shows that the finite span of a liquid-vapor or liquid-liquid interface needs to be considered to interpret experimental data collected with L ∼ κ −1 .

show abstract

Particle detachment from fluid interfaces: theory vs. experiments

Cited by 53 publications

References 44 publications

Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

Universal emulsion stabilization from the arrested adsorption of rough particles at liquid-liquid interfaces

Role of air‐water interfaces in colloid transport in porous media: A review

Capillary forces on a small particle at a liquid-vapor interface: Theory and simulation

Contact Info

Product

Resources

About