On the collapse pressure of armored bubbles and drops

Pitois, Olivier; Buisson, Manuel; Château, Xavier

doi:10.1140/epje/i2015-15048-9

Cited by 38 publications

(73 citation statements)

References 24 publications

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“…This result strongly differs from that of conventional armored drops and bubbles [14,[16][17][18] and soap bubbles for which Laplace's law applies, i.e., ΔP cap ¼ 8γ=D b . This behavior can be explained by compressive stress developing in the compact particle monolayer and balancing surface tension forces [14,16]. During inflation experiments, gas marbles go through a first regime, denoted "a" in Fig.…”

contrasting

confidence: 59%

“…As the resistance against collapse is probed, the decrease of the internal pressure is balanced by the compressive stress due to particle contacts in the monolayer, i.e., σ p < 0, as observed for classical armored bubbles and drops [14,16,18]. However, the cohesive nature of the shell allows for the collapse pressure to drastically increase with respect to reported collapse pressure values.…”

Section: Fig 4 Normalized Critical Overpressures (δPmentioning

confidence: 83%

“…Similarly to their liquid counterparts, the dissolution of those bubbles can be reduced or even stopped, and their shape can be nonspherical [15], revealing the mechanical stability of the protecting shell. Dedicated experiments have probed the corresponding mechanical strength: It has been shown that armored drops or bubbles of diameter D b can oppose liquid and gas removal up to applied pressures equal to 4γ=D b , i.e., the Laplace pressure of the particle-free drop or bubble with γ being the surface tension of the liquid-gas interface [14,[16][17][18]. For larger particle-to-drop or bubble size ratio, i.e., D P =D b ≥ 0.1, faceted morphologies and granular arches occur, and the magnitude of the collapse pressure increases up to twice the Laplace pressure [14,16].…”

mentioning

confidence: 99%

“…The measured values for the critical pressure, that gas marbles can sustain within inflation or deflation processes, are approximatively the same in absolute value. For negative pressures, with respect to liquid marbles [16][17][18], the stability range is increased by a factor of 10, revealing therefore exceptional properties for resisting against collapse. But, obviously, the The inner pressure decreases quasilinearly with ΔV down to a critical pressure difference ΔP − .…”

mentioning

confidence: 99%

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Gas Marbles: Much Stronger than Liquid Marbles

2017

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contrasting

confidence: 59%

Section: Fig 4 Normalized Critical Overpressures (δPmentioning

confidence: 83%

mentioning

confidence: 99%

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confidence: 99%

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Gas Marbles: Much Stronger than Liquid Marbles

2017

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“…This suggests that strategies to impart a resistance to dilation or compression of the interface would retard or entirely stop Ostwald ripening. Previously, fully covered, "jammed," particle coated bubbles were shown to fully resist dissolution of this nature (8)(9)(10)(11)(12). When the ratio of particle size to bubble size is large (a/R > 0.1), specific faceted shapes may moreover reduce the mean curvature to zero, thereby reducing the driving force to zero (10).…”

mentioning

confidence: 99%

Arresting dissolution by interfacial rheology design

Beltramo

Gupta

Alicke

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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A strategy to halt dissolution of particle-coated air bubbles in water based on interfacial rheology design is presented. Whereas previously a dense monolayer was believed to be required for such an "armored bubble" to resist dissolution, in fact engineering a 2D yield stress interface suffices to achieve such performance at submonolayer particle coverages. We use a suite of interfacial rheology techniques to characterize spherical and ellipsoidal particles at an air-water interface as a function of surface coverage. Bubbles with varying particle coverages are made and their resistance to dissolution evaluated using a microfluidic technique. Whereas a bare bubble only has a single pressure at which a given radius is stable, we find a range of pressures over which bubble dissolution is arrested for armored bubbles. The link between interfacial rheology and macroscopic dissolution of ∼ 100 µm bubbles coated with ∼ 1 µm particles is presented and discussed. The generic design rationale is confirmed by using nonspherical particles, which develop significant yield stress at even lower surface coverages. Hence, it can be applied to successfully inhibit Ostwald ripening in a multitude of foam and emulsion applications.interfacial rheology | foams | yield stress | Ostwald ripening | emulsions T uning the interparticle interaction potential in bulk suspensions has long been a strategy to engineer the properties of colloidal suspensions. In this work, we apply this paradigm to interfacial materials, specifically particle-stabilized drops and bubbles. These systems with high interfacial area have broad applicability from food formulation and processing (1, 2), encapsulation (3, 4), ultrasound medical technologies (5), to lowweight/high-strength materials (6). One of the key challenges in using solid stabilized emulsions and foams in applications is curtailing Ostwald ripening, which causes the growth/shrinkage of large/small bubbles and increased size heterogeneity (7).Ripening occurs due to differences in the Laplace pressure in bubbles of different radii; large bubbles grow, while small bubbles shrink. This suggests that strategies to impart a resistance to dilation or compression of the interface would retard or entirely stop Ostwald ripening. Previously, fully covered, "jammed," particle coated bubbles were shown to fully resist dissolution of this nature (8)(9)(10)(11)(12). When the ratio of particle size to bubble size is large (a/R > 0.1), specific faceted shapes may moreover reduce the mean curvature to zero, thereby reducing the driving force to zero (10). However, stability is also observed at much smaller a/R ratios, suggesting other factors come into play. Previous work supposed the particles do not interact with each other, but since such interactions have a major role in interfacial rheology, they can potentially contribute to bulk bubble and emulsion stability as well.Here, we design and characterize model viscoplastic interfacial systems consisting of spherical and nonspherical particles at an air-water int...

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Yield stress of aerated cement paste

Feneuil

Roussel

Pitois

2020

Cement and Concrete Research

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Yield stress of aerated cement paste is studied. Samples are prepared by mixing aqueous foam with cement paste, which allows controlling bubble size, gas volume fraction and yield stress of the cement paste. Two distinct behaviors are observed depending on the surfactant used to prepare the precursor aqueous foam: (i) For a surfactant with low adsorption ability with respect to cement grains, bubbles tend to decrease the yield stress of the paste with magnitude governed by the Bingham capillary number, which accounts for bubble deformability. (ii) For a surfactant with high adsorption ability, bubbles increase significantly the yield stress. This behavior is shown to result from the surfactant-induced hydrophobization of the cement grains, which adsorb at the surface of the bubbles and tend to rigidify them. Within this regime, the effect of air incorporation is comparable to the effect of added solid particles.

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On the collapse pressure of armored bubbles and drops

Cited by 38 publications

References 24 publications

Gas Marbles: Much Stronger than Liquid Marbles

Gas Marbles: Much Stronger than Liquid Marbles

Arresting dissolution by interfacial rheology design

Yield stress of aerated cement paste

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