Connect the Drops:  Using Solids as Adhesives for Liquids

Stancik, Edward J.; Fuller, Gerald G.

doi:10.1021/la049778e

Cited by 94 publications

(93 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As the bubble approaches closer to the wall, the liquid layer between the bubble and the wall thins (figure 6). Below the critical thickness of this liquid layer, a three-phase (gas-liquidsolid) contact (TPC) is formed, the dynamics of which is an important phenomenon used in (i) adhesion, spreading of droplets and bubbles on solid substrate (Wasan & Nikolov 2003;Stancik & Fuller 2004) and (ii) bubble-particle flotation separation processes (Leja 1982;Nguyen & Schulze 2004;Malysa, Kraswska & Krzan 2005;. The temporal rate of change in the thickness (h l ) of the liquid layer between the (no-slip) soild wall and gas bubble (free surface) has been suggested by Sheludko (1967), as…”

Section: Sliding Bubblesmentioning

confidence: 99%

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Jeong

Park

2015

J. Fluid Mech.

View full text Add to dashboard Cite

The dynamics of a large deformable bubble (Re ∼ O(10 3 )) rising near a vertical wall in quiescent water is experimentally investigated. The reference (without the wall) rising path of the considered bubble is a two-dimensional zigzag. For a range of wall configurations (i.e. initial wall distance and boundary condition), using high-speed shadowgraphy, various rising behaviours such as periodic bouncing, sliding, migrating away, and non-periodic oscillation without collisions are measured and analysed. Unlike low-Reynolds-and Weber-number bubbles, the contribution of the surface deformation to the transport between the energy components becomes significant during the bubble's rise. In particular, across the bubble-wall collision, the excess surface energy compensates the deficit of kinetic energy. This enables a large deformable bubble to maintain a relatively constant bouncing kinematics, despite the obvious wall-induced energy dissipation. The wall effect, predominantly appearing as energy loss, is found to decrease as the initial distance from the bubble centre to the wall increases. Compared to the regular (no-slip) wall, a hydrophobic surface enhances or reduces the wall effect depending on the wall distance, whereas a porous surface reduces the energy loss due to the wall, regardless of the initial distance from the wall. Furthermore, the bubble-wall collision behaviour is assessed in terms of a restitution coefficient and modified impact Stokes number (ratio of the inertia to viscous forces), which shows a good correlation, the trends of which agree well with the variations in the energy components. The dependence of near-wall bubble motion on the wall distance and boundary condition may suggest a way of predicting or controlling the near-wall gas void-fraction distribution in gas-liquid flow systems.

show abstract

Section: Sliding Bubblesmentioning

confidence: 99%

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Jeong

Park

2015

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…For instance, liquid drops coated with a fine hydrophobic powder become non-wetting [1], forming an artificial analog of a much older solution stumbled upon by insects [2]. Similarly, the addition of particles to the surface of liquid drops prior to coalescence stabilises the coalesced drops to the common pinch-off instability and can lead to reversible morphological instabilities such as buckling when subject to pressure [3]. Particle covered interfaces also occur at an intermediate stage during the production of colloidosomes [4], armored bubbles [5] and porous particle aerosols for drug delivery [6].…”

mentioning

confidence: 99%

Dynamics of Surfactant-Driven Fracture of Particle Rafts

et al. 2006

View full text Add to dashboard Cite

We investigate the dynamic fracture of a close-packed monolayer of particles, or particle raft, floating at a liquid-gas interface induced by the localised addition of surfactant. Unusually for a two-dimensional solid, our experiments show that the speed of crack propagation here is not affected by the elastic properties of the raft. Instead it is controlled by the rate at which surfactant is advected to the crack tip by means of the induced Marangoni flows. Further, the velocity of propagation is not constant in time and the length of the crack scales as t 3/4 . More broadly, this surfactant induced rupture of interfacial rafts suggests ways to manipulate them for applications.The curious behavior of particulate interfaces that separate liquids is a source of interesting questions at the intersection of hydrodynamics and elasticity. For instance, liquid drops coated with a fine hydrophobic powder become non-wetting [1], forming an artificial analog of a much older solution stumbled upon by insects [2]. Similarly, the addition of particles to the surface of liquid drops prior to coalescence stabilises the coalesced drops to the common pinch-off instability and can lead to reversible morphological instabilities such as buckling when subject to pressure Recent experiments [7,8] show that a densely packed monolayer of particles at an interface (a 'particle raft') has many of the characteristics of a two-dimensional linear elastic solid in certain regimes. For example, under compressive loading, a particle raft statically buckles out of the plane demonstrating that collectively its constituent particles possess a non-zero shear modulus, with γ the surface tension coefficient of the pure liquid-gas interface and d the particle diameter. This ability to sustain finite shear stresses arises from a combination of capillary forces and the short range steric constraints due to particle-particle contact, and is seen in a variety of similar systems such as armored bubbles, drying colloidal drops and suspensions [5,9,10,11], although understanding the kinetics of onset of this elastic behavior constitutes work in progress. Going beyond the linear elastic behavior, the ability to sustain finite shear stresses suggests that these rafts should also be able to sustain fractures which relieve stresses primarily in one direction [8]. This fracture can be observed in the particulate scum that forms on the surface of a cup of black tea, which is then fractured by the addition of milk. A similar phenomenon is observed in pond scum when fractured by the ripples induced by a pebble. Here we use an interfacial particle raft as a vehicle to study the cracks induced by the addition of surfactant and provide a model for

show abstract

“…59,60 When R974 particles occupy the interface and cover the surface of PS droplets, the interface between PP and PS becomes rigid, so the drainage process will becomes much slower. It has been established that the mobility of the interface is a critical parameter inuencing the drainage process.…”

Section: Discussion On the Stabilization Mechanismmentioning

confidence: 99%

“…[23][24][25][26][27][28] Inspired by this, in our previous studies, we introduced nano-silica particles into PP/PS blends and studied the effect of the particles on the morphology coarsening. In low viscosity liquid emulsions, a lot of studies have shown that inorganic particles can stabilize the emulsion morphology against coalescence.…”

Section: Introductionmentioning

confidence: 99%

Suppressing phase coarsening in immiscible polymer blends using nano-silica particles located at the interface

et al. 2015

View full text Add to dashboard Cite

The morphologies of polymer blends generated during processing are usually unstable and phase coarsening often occurs in the melt state, so suppressing the morphology coarsening is crucial to obtain polymer blends with tailored and stable structure and properties. The effect of nano-silica particles located at the interface on the phase coarsening of a polypropylene (PP)/polystyrene (PS) blend was studied in this work. In co-continuous 50/50 PP/PS blend, the particles at the interface can effectively suppress the coarsening process even at a very low particle loading. Real-time observation conducted by using an optical microscope equipped with a camera and a hot stage showed that a small loading of particles has little effect on the retraction process but can suppress the coalescence and at high loading of particles, both the retraction and coalescence process can be significantly suppressed. The suppressing effect towards the coalescence was confirmed in 70/30 blend with PS phase as the dispersed phase. The stabilization mechanism used in particle stabilized emulsions was adopted to explain the suppressing effect of nano-silica particles located at the interface towards the phase coarsening of PP/PS blends. 28 8546 0130; Tel: +86 28 8546 0130 † Electronic supplementary information (ESI) available. See

show abstract

Connect the Drops: Using Solids as Adhesives for Liquids

Cited by 94 publications

References 20 publications

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Near-wall rising behaviour of a deformable bubble at high Reynolds number

Dynamics of Surfactant-Driven Fracture of Particle Rafts

Suppressing phase coarsening in immiscible polymer blends using nano-silica particles located at the interface

Contact Info

Product

Resources

About