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Lum, Ka; Chandler, David

doi:10.1023/a:1022643006849

Cited by 54 publications

(69 citation statements)

References 20 publications

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“…[15] The smallest hydrophobic domain area capable of inducing a cavity between the two plates, is found to be 1.04×1.04 nm 2 (see Fig 3 (d)), which is consistent with the first cavitation in pattern III (Fig 3 (c) when d = 0.68 nm). Comparing the distances at which each cavity is formed during the association of the two plates for pattern II and pattern III, we find that stepwise cavitation for each pattern occurs at inter-plate distances which are linearly correlated with N nn .…”

Section: Resultssupporting

confidence: 75%

Hydrophobic Interactions and Dewetting between Plates with Hydrophobic and Hydrophilic Domains

2009

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We study by molecular dynamics simulations the wetting/dewetting transition and the dependence of the free energy on distance between plates that contain both hydrophobic and hydrophilic particles. We show that dewetting and strength of hydrophobic interaction is very sensitive to the distribution of hydrophobic and hydrophilic domains. In particular, we find that plates characterized by a large domain of hydrophobic sites induce a dewetting transition and an attractive solvent-induced interaction. On the other hand, a homogeneous distribution of the hydrophobic and hydrophilic particles on the plates prevents the dewetting transition and produces a repulsive solvent-induced interaction. We also present results for a kind of "Janus interface" in which one plate consists of hydrophobic particles and the other of hydrophilic particles showing that the inter-plate gap remains wet until steric constraints at small separations eject the water molecules.Our results indicate that the Cassie equation, for the contact angle of a heterogeneous plate, can not be used to predict the critical distance of dewetting. These results indicate that hydrophobic interactions between nanoscale surfaces with strong large length-scale hydrophobicity can be highly cooperative and thus they argue against additivity of the hydrophobic interactions between different surface domains in these cases.

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Section: Resultssupporting

confidence: 75%

Hydrophobic Interactions and Dewetting between Plates with Hydrophobic and Hydrophilic Domains

2009

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“…These trends are in qualitative agreement with direct Glauber dynamics sampling of the tube formation time. Our simulation results for the free energy barrier of tube formation point to limitations of the continuum model [34], which always (and erroneously) enforces a vapor tube geometry. Furthermore, because of the small length scales involved, it is important to account for the effects of fluctuations and the microscopic details of the model.…”

Section: Discussionmentioning

confidence: 81%

“…The evaporation then proceeds by the growth of the quasi-two dimensional nucleus. Using geometric arguments, the free energy barrier at the transition state, AG*, and the critical tube radius, r., can be estimated by [16,34] AG* = n-y(ll -2~)2/6,…”

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confidence: 99%

Dynamics of capillary evaporation. I. Effect of morphology of hydrophobic surfaces

Luzar

Leung

2000

The Journal of Chemical Physics

115

137

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Cavitation has been suggested to be a possible source of long range interactions between mesoscopic hydrophobic surfaces. While evaporation is predicted by thermodynamics,little is known about its kinetics. Glauber dynamics Monte Carlo simulationsof a lattice gas close to liquid-gascoexistence and confined between partially drying surfacesare used to model the effect of water confinement on the dynamics of surface-inducedphase transition. Specifically, we examine how kinetics of induced evaporation change as the texture of hydrophobic surfacesis varied. Evaporationrates are considerably slowed with relatively small amount of hydrophilic coverage. However, the distribution of hydrophilic patches is found to be crucial, with the homogeneous one being much more effectivein slowingthe formation of vapor tubes which triggersthe evaporationprocess. We estimatethe fi-eeenergy barrierof vapor tube formation via transitionstate theory,usinga constrainedforwardbackward umbrella sampling technique applied to the metastable, confined liquid. Furthermore,to relate simulationrates to experimentalones, we perform simulationsusing the mass-conservingKawasakialgorithm. We predict evaporation time scales that range horn hundredsof picosecond in the case of mesoscopic surfacesN 104 nm2 to tens of nanosecondsfor smaller surfaces N 40 nm2, when the two surfacesare w 10 solvent layersapart. The present study demonstrates that cavitation is kinetically viable in real systems and should be considered in studies of processesat confined geometry. I.

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“…Ascribing the sheet resistance to ionic substances presented on a surface at (surface) concentration N s should result in the sheet resistance being inversely proportional to N s and the ion mobility, μ. For the latter it is common to use the Einstein relation expressing μ via a diffusion coefficient, D s : μ = eD s / k B T. Thus the sheet resistance is inversely proportional to both, N s and D s : (11) Obviously R s can be very high, up to infinity at N s = 0, but how low can it be? Can it be lower than the value corresponding to R min ?…”

Section: Discussionmentioning

confidence: 99%

Electrical Conductance of Hydrophobic Membranes or What Happens below the Surface

et al. 2007

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Nanoporous alumina membranes rendered hydrophobic by surface modification via covalent attachment of hydrocarbon or fluorocarbon chains conduct electricity via surface even when the pores are not filled with electrolyte. The resistance is many orders of magnitude higher than for electrolyte filled membranes and does not depend on the electrolyte concentration or pH but it does depend on the type of hydrophobic monolayer and its density. The corresponding surface resistance varies from greater than 10 18 Ω/□ to less than 3×10 9 Ω/□. When the hydrophobic monolayer contains a small proportion of photoactive spiropyran that is insufficient to switch the surface to hydrophilic after spiropyran photoisomerization to the merocyanine form, the membrane resistance also becomes light-dependent with a reversible increase of surface resistance by as much as 15%. Surface conduction is ascribed to hydration and ionization of the alumina surface hydroxyls and the ionizable groups of the hydrophobic surface modifiers.

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Untitled

Cited by 54 publications

References 20 publications

Hydrophobic Interactions and Dewetting between Plates with Hydrophobic and Hydrophilic Domains

Hydrophobic Interactions and Dewetting between Plates with Hydrophobic and Hydrophilic Domains

Dynamics of capillary evaporation. I. Effect of morphology of hydrophobic surfaces

Electrical Conductance of Hydrophobic Membranes or What Happens below the Surface

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