Nanoscale adhesive forces between silica surfaces in aqueous solutions

Troncoso, Paula; Saavedra, Jorge H.; Acuña, Sergio; Jeldres, Ricardo I.; Concha, F.; Toledo, Pedro G.

doi:10.1016/j.jcis.2014.03.020

Cited by 14 publications

(7 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our derived laws for the cavitation transition and the dry adhesion transition both depend on the sum of the contact angles of the two surfaces, in good agreement with explicit simulation results for not too asymmetric surfaces. This means that the regime of dry adhesion without cavitation in the adhesion state diagram spanned by the two surface contact angles forms a strip between the hydration repulsion and cavitation regimes, in good agreement with a host of experimental findings for different systems (2,3,(22)(23)(24)(25)(26). Our theoretical analysis shows that this dry adhesion regime necessarily exists and that it becomes more pronounced the stronger the direct surface-surface interactions are.…”

Section: Discussionsupporting

confidence: 87%

“…Most practical situations involve two dissimilar surfaces, for example nanoparticles interacting with cell membranes (20) or weak protein-protein interactions (21). In fact, a number of experimental model studies addressed the interactions between dissimilar surfaces and the particularly interesting case of hydrophobic-hydrophilic surfaces (2,3,(22)(23)(24)(25)(26). The results are rather multifaceted and cannot be easily cast in a unified picture, yet, in one study an empirical sum rule for the interaction strength between two dissimilar surfaces in terms of the two surface contact angles was established (22).…”

mentioning

confidence: 99%

See 1 more Smart Citation

From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces

Kanduč

Netz

2015

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

View full text Add to dashboard Cite

Using all-atom molecular dynamics (MD) simulations at constant water chemical potential in combination with basic theoretical arguments, we study hydration-induced interactions between two overall chargeneutral yet polar planar surfaces with different wetting properties. Whether the water film between the two surfaces becomes unstable below a threshold separation and cavitation gives rise to long-range attraction, depends on the sum of the two individual surface contact angles. Consequently, cavitation-induced attraction also occurs for a mildly hydrophilic surface interacting with a very hydrophobic surface. If both surfaces are very hydrophilic, hydration repulsion dominates at small separations and direct attractive force contribution can-if strong enough-give rise to wet adhesion in this case. In between the regimes of cavitation-induced attraction and hydration repulsion we find a narrow range of contact angle combinations where the surfaces adhere at contact in the absence of cavitation. This dry adhesion regime is driven by direct surface-surface interactions. We derive simple laws for the cavitation transition as well as for the transition between hydration repulsion and dry adhesion, which favorably compare with simulation results in a generic adhesion state diagram as a function of the two surface contact angles.A ccording to the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the interaction between hydrated surfaces is given by the sum of van der Waals (vdW) and screened electrostatic interactions (1). Although this approach works well in many situations, subnanometer resolved force measurements between individual surfaces demonstrated that additional watermediated interactions are dominant at small separations and depend crucially on the polarity or wetting properties of the surfaces (2-4). Understanding these solvation-induced interactions is still a central issue in all fields concerned with forces between surfaces, colloids, and macromolecular aggregates in water.As is well known, the water film between two hydrophobic surfaces, characterized by water contact angles θ > 90°, becomes freeenergetically unstable below a critical distance and in equilibrium cavitation leads to vapor bubble-induced long-ranged attraction (5-7). Conversely, polar and overall neutral surfaces, characterized by small or vanishing contact angles, exhibit pronounced shortranged repulsive forces, which decay exponentially with a characteristic length in the subnanometer range (8-11). These so-called hydration forces arise from the complex interplay of surface group configurational degrees of freedom, desorption of hydration water from polar surface groups, and ordering of the intersurface water film (4). The understanding of hydration forces has recently been advanced by computer simulations that include explicit water molecules (12)(13)(14).In the absence of direct surface-surface interactions, the transition between cavitation-induced attraction and hydration repulsion should coincide with the contact angle char...

show abstract

Section: Discussionsupporting

confidence: 87%

mentioning

confidence: 99%

From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces

Kanduč

Netz

2015

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

View full text Add to dashboard Cite

show abstract

“…For instance, Lucay et al [10] reported that NaCl decreased the electrostatic repulsion between bubbles and the molybdenite particles, enhancing its flotation kinetics and recovery. In addition, increased hydrophobicity of some minerals treated in a saline environment was found by Troncoso [19]. Moreover, Liu et al [12] and Ramos et al [20] reported that salt ions at high concentrations inhibited bubble coalescence and stabilized the froth layer, further increasing mineral recovery.…”

Section: Introductionmentioning

confidence: 90%

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Wei

et al. 2018

Minerals

View full text Add to dashboard Cite

Seawater has been considered as an alternative to freshwater for flotation. However, many ions in seawater were reported to depress molybdenite (MoS2), with the depressing mechanisms being insufficiently understood. In this study, the influence of divalent ions (e.g., Ca2+ and Mg2+) and dispersant on MoS2 flotation was systematically investigated. It was found that the detrimental effects of Ca2+ and Mg2+ on the natural flotability of MoS2 were mainly due to the attachment of formed CaMoO4 precipitates and Mg(OH)2 colloids onto MoS2 surface. However, the addition of sodium hexametaphosphate (SHMP) reduced the negative effects. Various measurements, including contact angle, zeta potential, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), were conducted to understand the influencing mechanisms of divalent ions and the beneficial effects of SHMP on MoS2 flotation. In addition, the Extended Derjguin–Landau–Verwey–Overbeek (EDLVO) theory was applied to investigate the total interaction energy between MoS2 particles and formed colloids, revealing that the reduced attraction force between MoS2 and Mg(OH)2 colloids in the presence of SHMP primarily resulted in the increased MoS2 recovery. In addition, SHMP combined with Mg2+ and Ca2+ to form dissolvable complexes, thereby reducing insoluble Mg2+ and Ca2+ compounds or precipitation. Thus, this study demonstrated for the first time two influencing mechanisms of SHMP in improving MoS2 recovery in the presence of Ca2+ and Mg2+.

show abstract

“…However, many real situations involve dissimilar surfaces, for example, weak protein–protein interactions, nanoparticles interacting with cell membranes, or membranes interacting with biominerals . Several experimental studies addressed the interactions between dissimilar surfaces and the particularly interesting case of hydrophobic–hydrophilic interfaces. − ,,− The results are very diverse and do not seem to fit into a universal picture. In this section, we address the asymmetric case, where the interacting surfaces have dissimilar polarities α 1 and α 2 .…”

Section: Asymmetric Interaction Scenariosmentioning

confidence: 99%

“…A more intricate picture emerges for asymmetric scenarios, where the interacting surfaces exhibit different contact angles. A number of experimental model studies addressed the interactions between dissimilar surfaces and the particularly interesting case of a hydrophobic surface interacting with a hydrophilic one. − ,,− …”

Section: Introductionmentioning

confidence: 99%

Water-Mediated Interactions between Hydrophilic and Hydrophobic Surfaces

et al. 2016

View full text Add to dashboard Cite

All surfaces in water experience at short separations hydration repulsion or hydrophobic attraction, depending on the surface polarity. These interactions dominate the more long-ranged electrostatic and van der Waals interactions and are ubiquitous in biological and colloidal systems. Despite their importance in all scenarios where the surface separation is in the nanometer range, the origin of these hydration interactions is still unclear. Using atomistic solvent-explicit molecular dynamics simulations, we analyze the interaction free energies of charge-neutral model surfaces with different elastic and water-binding properties. The surface polarity is shown to be the most important parameter that not only determines the hydration properties and thereby the water contact angle of a single surface but also the surface-surface interaction and whether two surfaces attract or repel. Elastic properties of the surfaces are less important. On the basis of surface contact angles and surface-surface binding affinities, we construct a universal interaction diagram featuring three different interaction regimes-hydration repulsion, cavitation-induced attraction-and for intermediate surface polarities-dry adhesion. On the basis of scaling arguments and perturbation theory, we establish simple combination rules that predict the interaction behavior for combinations of dissimilar surfaces.

show abstract

Nanoscale adhesive forces between silica surfaces in aqueous solutions

Cited by 14 publications

References 42 publications

From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces

From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces

Fundamental Studies of SHMP in Reducing Negative Effects of Divalent Ions on Molybdenite Flotation

Water-Mediated Interactions between Hydrophilic and Hydrophobic Surfaces

Contact Info

Product

Resources

About