Phase separation in fluids exposed to spatially periodic external fields

Vink, R. L. C.; Archer, Andrew J.

doi:10.1103/physreve.85.031505

Cited by 6 publications

(7 citation statements)

References 37 publications

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“…11 Actively controlling these interfacial phenomena, however, has not yet been achieved in colloidal systems. [23][24][25] Here, we use optical trapping to actively deform the uid-uid interface in a phase separated aqueous colloid-polymer mixture with an ultra-low interfacial tension. Examples include interface distortions with an atomic force microscopy probe, 12-14 electric eld tweezers 15 or a magnetic sphere above a magnetic particle-laden liquid surface.…”

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confidence: 99%

Optical trapping of interfaces at ultra-low interfacial tension

et al. 2015

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We achieve active control of interfacial phenomena by optically trapping the interface using the gradient forces of a strongly focussed laser beam parallel to the interface. We illustrate our technique in a phase separated colloid-polymer mixture by distorting the interface in a very controlled way. The static structure of the manipulated interface as well as its dynamic relaxation behaviour are analysed. Both the statics and dynamics can be related to the capillary wave height-height correlation functions using the fluctuation dissipation theorem up to surprisingly large deformations of the interface. To underline the novelty and potential of our approach we also show multiple interface distortions and the controlled snap-off of liquid droplets.

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confidence: 99%

Optical trapping of interfaces at ultra-low interfacial tension

et al. 2015

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“…A recent paper [55] on fluids in periodic confinement showed unexpected correlations between the channels that deserve further investigation in the current system.…”

Section: Discussionmentioning

confidence: 80%

“…11,56,57 Given the nite system size as well as the nite wedge geometry our assumption is completely reasonable, but an extension of this work would be to analyse the wetting and wedge lling behaviour of a single corrugated wall and compare to works on wedge lling transition in nite geometries. [58][59][60] A recent paper 55 on uids in periodic connement showed unexpected correlations between the channels that deserve further investigation in the current system.…”

Section: Discussionmentioning

confidence: 82%

Effect of controlled corrugation on capillary condensation of colloid–polymer mixtures

Fortini

Schmidt

2013

Soft Matter

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We investigate with Monte Carlo computer simulations the capillary phase behaviour of model colloid-polymer mixtures confined between a flat wall and a corrugated wall. The corrugation is modelled via a sine wave as a function of one of the in-plane coordinates leading to a depletion attraction between colloids and the corrugated wall that is curvature dependent. We find that for increased amplitude of corrugation the region of the phase diagram where capillary condensation occurs becomes larger. We derive a Kelvin equation for this system and compare its predictions to the simulation results. We find good agreement between theory and simulation indicating that the primary reason for the stronger capillary condensation is an increased contact area between the fluid and the corrugated substrate. On the other hand, the colloid adsorption curves at colloid gas-liquid coexistence show that the increased area is not solely responsible for the stronger capillary condensation. Additionally, we analyse the dimensional crossover from a quasi-2D to a quasi-1D system and find that the transition is characterised by the appearance of a metastable phase. arXiv:1301.7434v2 [cond-mat.soft]

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“…Here, the spatial location of the liquids directly ties to the free energy, and as a consequence, the total free energy can have a single minimum even with two-phase coexistence. We point out that not all spatially nonuniform fields display this property, as for example in the case of random-field [17] and periodicfield [18] Ising models.…”

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confidence: 93%

Mixing-demixing phase diagram for simple liquids in nonuniform electric fields

Galanis

Tsori

2013

Phys. Rev. E

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We deduce the mixing-demixing phase diagram for binary liquid mixtures in an electric field for various electrode geometries and arbitrary constitutive relation for the dielectric constant. By focusing on the behavior of the liquid-liquid interface, we produce simple analytic expressions for the dependence of the interface location on experimental parameters. We also show that the phase diagram contains regions where liquid separation cannot occur under any applied field. The analytic expression for the boundary "electrostatic binodal" line reveals that the regions' size and shape depend strongly on the dielectric relation between the liquids. Moreover, we predict the existence of an "electrostatic spinodal" line that identifies conditions where the liquids are in a metastable state. We finally construct the phase diagram for closed systems by mapping solutions onto those of an open system via an effective liquid composition. For closed systems at a fixed temperature and mixture composition, liquid separation occurs in a finite "window" of surface potential (or charge density). Higher potentials or charge densities counterintuitively destroy the interface, leading to liquid mixing. These results give valuable guides for experiments by providing easily testable predictions for how liquids behave in nonuniform electric fields.

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Phase separation in fluids exposed to spatially periodic external fields

Cited by 6 publications

References 37 publications

Optical trapping of interfaces at ultra-low interfacial tension

Optical trapping of interfaces at ultra-low interfacial tension

Effect of controlled corrugation on capillary condensation of colloid–polymer mixtures

Mixing-demixing phase diagram for simple liquids in nonuniform electric fields

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