Intrusion and extrusion of water in hydrophobic mesopores

Lefèvre, Benoît; Saugey, Anthony; Barrat, Jean‐Louis; Bocquet, Lydéric; Charlaix, Élisabeth; Gobin, P.F.; Vigier, G.

doi:10.1063/1.1643728

Cited by 186 publications

(311 citation statements)

References 24 publications

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“…A few comments are in order. First the negative sign of the line tension is in agreement with previous observations [19,15]. Moreover, the order of magnitude is consistent with these previous estimates.…”

Section: Nucleation Barriersupporting

confidence: 92%

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Nucleation in Hydrophobic Cylindrical Pores: A Lattice Model

2005

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We consider the nucleation process associated with capillary condensation of a vapor in a hydrophobic cylindrical pore (capillary evaporation). The liquid-vapor transition is described within the framework of a simple lattice model. The phase properties are characterized both at the mean-field level and using Monte-Carlo simulations. The nucleation process for the liquid to vapor transition is then specifically considered. Using umbrella sampling techniques, we show that nucleation occurs through the condensation of an asymmetric vapor bubble at the pore surface. Even for highly confined systems, good agreement is found with macroscopic considerations based on classical nucleation theory. The results are discussed in the context of recent experimental work on the extrusion of water in hydrophobic pores.

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Section: Nucleation Barriersupporting

confidence: 92%

“…This shows that the nucleation process occurs via the creation of a vapor bubble on the wall. It is important to emphasize that the nucleus breaks the cylindrical symmetry of the system, in contrast to simple expectations [15].…”

Section: Nucleation Pathmentioning

confidence: 89%

Nucleation in Hydrophobic Cylindrical Pores: A Lattice Model

2005

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“…These model materials have been used as nanoscale laboratory to study the phase diagram of confined liquids (20,21). In previous works (22,23), we used silane-grafted MCM-41 (Mobil Crystalline Material 41) to study water confined by hydrophobic walls. Liquid water penetrates into the nanopores at high pressure, reaching 500 bars for nanometer-sized pores.…”

mentioning

confidence: 99%

Activated drying in hydrophobic nanopores and the line tension of water

Guillemot

Biben

Galarneau

et al. 2012

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

125

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We study the slow dynamics of water evaporation out of hydrophobic cavities by using model porous silica materials grafted with octylsilanes. The cylindrical pores are monodisperse, with a radius in the range of 1-2 nm. Liquid water penetrates in the nanopores at high pressure and empties the pores when the pressure is lowered. The drying pressure exhibits a logarithmic growth as a function of the driving rate over more than three decades, showing the thermally activated nucleation of vapor bubbles. We find that the slow dynamics and the critical volume of the vapor nucleus are quantitatively described by the classical theory of capillarity without adjustable parameter. However, classical capillarity utterly overestimates the critical bubble energy. We discuss the possible influence of surface heterogeneities, long-range interactions, and high-curvature effects, and we show that a classical theory can describe vapor nucleation provided that a negative line tension is taken into account. The drying pressure then provides a determination of this line tension with much higher precision than currently available methods. We find consistent values of the order of −30 pN in a variety of hydrophobic materials. A remarkable property of water is its ability to form nanosize bubbles, or cavities, on hydrophobic bodies (1). Since their first direct observations through atomic force microscopy about a decade ago (2, 3), surface nanobubbles on hydrophobic surfaces have raised considerable interest, and they are believed to play a major role in surface-driven phenomena, such as boundary slippage of water flows, heat transfer at walls, vaporization and boiling, surface cleaning, etc. (4, 5). In a different context, the evaporation of water in the vicinity of hydrophobic bodies has been studied as a core mechanism for the hydrophobic interaction mediated by water (6-8), which plays a central role in biological matter. The formation of cavities able to bridge hydrophobic units provides a driving force for protein folding and supermolecular aggregation (9). Simulation examples of such drying-induced phenomena include the collapse of a polymer chain, multidomain proteins, and hydrophobic particles (9-13).Despite their direct observation, the easy formation and the high stability of nanobubbles on hydrophobic bodies still raise fundamental questions (5,14,15). Because of significant theoretical work, it is now established that, at the scale of the nanometer, macroscopic concepts apply: hydrophobicity is described by interfacial energies, and the drying transition in hydrophobic confinement is a first-order transition triggered by the nucleation of a critical vapor bubble (1). The energy barrier limiting the kinetics of this transition is a strong signature of nanobubbles properties. Evaporation kinetics has also been pointed out as the most direct measure of the importance of hydrophobic collapse in protein folding (9). However, rate effects in the drying transition have not received much attention. A few numerical studies have addr...

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“…The closed cycle and, consequently, the complete transformation of the work into the heat was observed for a number of water-hydrophobized silica gel systems [7,17,18,21,22]. In particular, the complete emptying of pores after the infiltration and the subsequent defiltration with a decrease in the excess pressure to zero was observed in [17,18] for the KSK-G silica gel modified by n-alkylsilane molecules (n = 8, 16) grafted to the silica gel surface with a surface density higher than 2 nm −2 .…”

Section: Conditions For the Closed Cyclementioning

confidence: 90%

“…The revealed difference between the infiltration and defiltration pressures and the absorption of the mechanical energy observed in the infiltration-defiltration cycle due to the pressure hysteresis, as a rule, have been explained by the hysteresis of the contact angle; however, the mechanism responsible for the appearance of the latter hysteresis has remained unclear [4,6,7,[19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Correlation effects during liquid infiltration into hydrophobic nanoporous media

Borman

Belogorlov

Byrkin

et al. 2011

J. Exp. Theor. Phys.

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Correlation effects arising during liquid infiltration into hydrophobic porous medium are considered. On the basis of these effects a mechanism of energy absorption at filling porous medium by nonwetting liquid is suggested. In accordance with this mechanism, the absorption of mechanical energy is a result expenditure of energy for the formation of menisci in the pores on the shell of the infinite cluster and expenditure of energy for the formation of liquidporous medium interface in the pores belonging to the infinite cluster of filled pores. It was found that in dependences on the porosity and, consequently, in dependences on the number of filled pores neighbors, the thermal effect of filling can be either positive or negative and the cycle of infiltration-defiltration can be closed with full outflow of liquid. It can occur under certain relation between percolation properties of porous medium and the energy characteristics of the liquid-porous medium interface and the liquid-gas interface. It is shown that a consecutive account of these correlation effects and percolation properties of the pores space during infiltration allow to describe all experimental data under discussion.

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Intrusion and extrusion of water in hydrophobic mesopores

Cited by 186 publications

References 24 publications

Nucleation in Hydrophobic Cylindrical Pores: A Lattice Model

Nucleation in Hydrophobic Cylindrical Pores: A Lattice Model

Activated drying in hydrophobic nanopores and the line tension of water

Correlation effects during liquid infiltration into hydrophobic nanoporous media

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