Stability Limits of Capillary Bridges: How Contact Angle Hysteresis Affects Morphology Transitions of Liquid Microstructures

Ruiter, Riëlle de; Semprebon, Ciro; Gorcum, Mathijs van; Duits, Michael H.G.; Brinkmann, Martin; Mugele, Friedrich Gunther

doi:10.1103/physrevlett.114.234501

Cited by 24 publications

(15 citation statements)

References 27 publications

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“…Physically, this observation arises from the fact that the energy landscape in which the drops are trapped is very shallow close to the critical conditions of release. As a consequence, small microscopic "friction" forces can have a very big effect on the macroscopic behavior (de Ruiter et al 2015).…”

Section: Resultsmentioning

confidence: 99%

“…To understand the transport of released oil drops in the porous rock medium, we also studied the interaction of freely flowing drops with specific topographic structures and wettability patterns on the walls of microfluidic channels (de Ruiter et al 2014). The experiments are carried out with a continuous oil phase that wets the channel walls completely such that the moving drops remain lubricated by a thin film of the continuous phase at all times.…”

Section: Resultsmentioning

confidence: 99%

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Insights From Ion Adsorption and Contact-Angle Alteration at Mineral Surfaces for Low-Salinity Waterflooding

et al. 2016

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Most solid surfaces acquire a finite surface charge after exposure to aqueous environments caused by desorption and/or adsorption of ionic species. The resulting electrostatic forces play a crucial role in many fields of science and technology, including colloidal stability, self-assembly, wetting, and biophysics. Enhanced oil recovery (EOR) is an example of a large-scale industrial process that hinges in many respects on these phenomena. In this paper, we present a series of experiments illustrating fundamental aspects of low-salinity waterflooding in well-defined model systems. We show how pH and ion content of the water phase as well as the presence of model polar components (fatty acids) in the oil phase affect the wettability (i.e., contact-angle distribution) of oil/water/rock systems. Specifically, we discuss high-resolution atomic-force microscopy (AFM) experiments demonstrating the preferential adsorption of multivalent cations to mineral surfaces such as mica and gibbsite. Cation adsorption leads to increased and, in some cases, reversed surface charge at the solid/liquid interface. In particular, the adsorption of divalent cations gives rise to charge reversal and thereby induces a transition from complete water-wetting in the absence to finite contact angles in the presence of such ions. Although already dramatic for pure alkanes as base oil, adding fatty acids to the oil phase enhances the effect of divalent ions on the oil/water/rock wettability even more. In this case, contact-angle variations of more than 70 can be observed as a function of the salt concentration. This enhancement is caused by the deposition of a thin film of fatty acid on the solid surface. AFM as well as surface plasmon-resonance spectroscopy measurement in a microfluidic continuous flow cell directly demonstrate that adsorbed Ca 2þ ions promote secondary adsorption of acidic components from the oil phase. The combination of the effects discussed provides a rational scenario explaining many aspects of the success of low-salinity waterflooding.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Insights From Ion Adsorption and Contact-Angle Alteration at Mineral Surfaces for Low-Salinity Waterflooding

et al. 2016

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“…In such a case, the requirement of a constant equilibrium contact angle over a solid surface imposes the constraint that, close to the contact line, the boundaries are solids of revolution about an axis passing through the centre of the sphere. It is straightforward to apply this criterion to find the force-free equilibrium states of capillary bridges between flat and curved walls [10][11][12][13][14][15], but also those of droplets in contact with suspended solid particles, such as Pickering emulsions [16] and liquid marbles [17,18].…”

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confidence: 99%

Energy Invariance in Capillary Systems

Ruiz-Gutiérrez

Guan

et al. 2017

Phys. Rev. Lett.

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We demonstrate the continuous translational invariance of the energy of a capillary surface in contact with reconfigurable solid boundaries. We present a theoretical approach to find the energyinvariant equilibria of spherical capillary surfaces in contact with solid boundaries of arbitrary shape and examine the implications of dynamic frictional forces upon a reconfiguration of the boundaries.Experimentally, we realise our ideas by manipulating the position of a droplet in a wedge geometry using lubricant-impregnated solid surfaces, which eliminate the contact-angle hysteresis and provide a test bed for quantifying dissipative losses out of equilibrium. Our experiments show that dissipative energy losses for an otherwise energy-invariant reconfiguration are relatively small, provided that the actuation timescale is longer than the typical relaxation timescale of the capillary surface. We discuss the wider applicability of our ideas as a pathway for liquid manipulation at no potential energy cost in low-pinning, low-friction situations.

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“…Third, the relaxation of the droplet upon a variation of the applied electric potential, or its complete removal, is likely to depend on the previous actuation history, leading to hysteresis. 11 Here, we study the transport of a water droplet immersed in an ambient oil phase as it undergoes a cycle of electrowetting and dewetting within a channel. To induce lateral transport in a preferred direction we use a wedge-shaped channel, [12][13][14][15][16][17][18] where the droplet displays inwards motion upon electrowetting, and outwards motion when the voltage is removed 19 (dewetting).…”

Section: Introductionmentioning

confidence: 99%