Adsorption Within and On Regularly Patterned Substrates

Bruschi, L.; Mistura, Giampaolo

doi:10.1007/s10909-009-9913-z

Cited by 24 publications

(30 citation statements)

References 55 publications

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“…In this paper we revisit the condensation of a fluid occurring in a capped capillary slit or equivalently in a macroscopically long groove of depth D and width L scored in a solid surface in contact with a bulk vapour. This has attracted considerable interest in the last decade where it has been shown, for example, that the condensation, that is the filling of the groove as the pressure is increased, is continuous when the walls are completely wet by liquid [10][11][12][13][14][15][16][17][18][19]. Here we revisit the first-order condensation occurring when the walls are partially wet corresponding to contact angle θ > 0.…”

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confidence: 99%

Modified Kelvin Equations for Capillary Condensation in Narrow and Wide Grooves

Malijevský

Parry

2018

Phys. Rev. Lett.

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We consider the location and order of capillary condensation transitions occurring in deep grooves of width L and depth D. For walls that are completely wet by liquid (contact angle θ=0) the transition is continuous and its location is not sensitive to the depth of the groove. However, for walls that are partially wet by liquid, where the transition is first order, we show that the pressure at which it occurs is determined by a modified Kelvin equation characterized by an edge contact angle θ_{E} describing the shape of the meniscus formed at the top of the groove. The dependence of θ_{E} on the groove depth D relies, in turn, on whether corner menisci are formed at the bottom of the groove in the low density gaslike phase. While for macroscopically wide grooves these are always present when θ<45° we argue that their formation is inhibited in narrow grooves. This has a number of implications including that the local pinning of the meniscus and location of the condensation transition is different depending on whether the contact angle is greater or less than a universal value θ^{*}≈31°. Our arguments are supported by detailed microscopic density functional theory calculations that show that the modified Kelvin equation remains highly accurate even when L and D are of the order of tens of molecular diameters.

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confidence: 99%

Modified Kelvin Equations for Capillary Condensation in Narrow and Wide Grooves

Malijevský

Parry

2018

Phys. Rev. Lett.

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“…Despite its commonplace occurrence, the origin of the hysteresis phenomenon is still a matter of debate 12,13 . According to macroscopic thermodynamic arguments 14 , the hysteresis is usually explained in terms of the different shape of the vapour/adsorbate interface during adsorption and desorption in a cylindrical pore with open ends 1,2 .…”

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confidence: 99%

Continuous adsorption in highly ordered porous matrices made by nanolithography

et al. 2013

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The exposed surface area of porous materials is usually determined by measuring the mass of adsorbed gas as a function of vapour pressure. Here we report a comprehensive study of adsorption in systems with closed bottom, not interconnected pores exhibiting different degrees of disorder, produced with methods encompassing nanolithography and dry and wet etching. Detailed adsorption studies of these matrices show hysteresis loops, as found always in pores having sizes of tens to hundreds of nanometres. The observed variations in the loop shape are associated with changes in the pore morphology. In regular pores formed by vertical and smooth walls, continuous adsorption is found for the first time in agreement with thermodynamic considerations valid for ideal pores. This suggests that irregularities in the walls and pore openings are the key factors behind the hysteresis phenomenon. Interestingly, pores having rough walls but a pyramidal shape also do not show any hysteresis.

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“…Here δµ ≡ µ − µ sat and β co is the (non-universal) critical exponent characterizing the divergence of the liquid film height; specifically, for systems where the interaction at long distances is dominated by non-retarded dispersion forces β co = 1/3. More recently, an attention has been focused on structured substrates, in which case a number of additional interfacial phenomena occur [7][8][9][10][11][12][13]. For example, for sinusoidally shaped walls the complete wetting may be preceded by an unbending transition, characterized by an abrupt flattening of the liquid-gas interface from the state at which the interface follows the shape of the wall, and which occurs provided the wall amplitude exceeds a certain critical value [14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…From a broader perspective, however, we will show that the entire adsorption process exhibits a number of additional interfacial phenomena and surface phase transitions, and that it can be divided into three parts. The first regime corresponds to filling of the grooves with a dense, liquidlike phase, a process which has recently attracted some attention [12,24,[32][33][34][35][36][37][38][39][40][41][42][43][44][45]. For a single macroscopically deep groove (or a capped capillary), D → ∞, the recent studies have shown that the filling is a first-order transition for temperatures below T w but continuous (critical) otherwise with a critical exponent β g = 1/4 characterizing the rate of the groove filling for systems including dispersion forces.…”

Section: Introductionmentioning

confidence: 99%

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

Malijevský

2020

Phys. Rev. E

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We study adsorption at periodically corrugated substrates formed by scoring rectangular grooves into a planar solid wall which interacts with the fluid via long-range (dispersion) forces. The grooves are assumed to be macroscopically long but their depth, width and separations can all be molecularly small. We show that the entire adsorption process can be divided into three parts consisting of (i) filling the grooves by a capillary liquid; (ii) depinning of the liquid-gas interface from the wall edges; and (iii) unbinding of the interface from the top of the wall, which is accompanied by a rapid but continuous flattening of its shape. Using a nonlocal density functional theory and mesoscopic interfacial models all the regimes are discussed in some detail to reveal the complexity of the entire process and subtle aspects that affect its behaviour. In particular, it is shown that the nature of the depinning phenomenon is governed by the width of the wall pillars (separating grooves), whilst the grooves width only controls the location of the depinning first-order transition, if present.

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Adsorption Within and On Regularly Patterned Substrates

Cited by 24 publications

References 55 publications

Modified Kelvin Equations for Capillary Condensation in Narrow and Wide Grooves

Modified Kelvin Equations for Capillary Condensation in Narrow and Wide Grooves

Continuous adsorption in highly ordered porous matrices made by nanolithography

Filling, depinning, unbinding: Three adsorption regimes for nanocorrugated substrates

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