Long-Range Hydrophobic Forces between Mica Surfaces in Dodecylammonium Chloride Solutions in the Presence of Dodecanol

Yoon, Roe‐Hoan; Ravishankar, Sadhana

doi:10.1006/jcis.1996.0230

Cited by 90 publications

(55 citation statements)

References 17 publications

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“…Comparable results were recently obtained in simulations, where the adhesion behavior was shown to depend crucially on the surface adhesion energy (19). A transition between dry adhesion and hydration repulsion was seen for typical surface contact angle values in the range of θ adh = 65°-85°, depending on the mechanical stiffness and the hydrogen-bonding capability of the surfaces (19), the values of θ adh being quite similar to those in experiments (15)(16)(17)(18).…”

supporting

confidence: 78%

“…In contrast, experiments probing the interactions between similar neutral surfaces with well-defined contact angles demonstrated that even hydrophilic surfaces exhibit short-range attractions not accountable by vdW forces down to typical adhesive contact angles of θ adh = 65°-80° (15)(16)(17)(18). Comparable results were recently obtained in simulations, where the adhesion behavior was shown to depend crucially on the surface adhesion energy (19).…”

mentioning

confidence: 71%

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

Kanduč

Netz

2015

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

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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...

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confidence: 78%

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confidence: 71%

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

Kanduč

Netz

2015

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

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“…The range and origin of this interaction has remained unresolved for 20 years (3,9,10). Suggested mechanisms for the long-range hydrophobic attraction include two mainly theoretical and two more experimental models as follows: (i) water structure (2,3,11), (ii) electrostatic models based on fluctuating dipoles (3,10,12,13), (iii) preexisting submicroscopic bubbles that bridge the surfaces (10,(14)(15)(16)(17), and (iv) the spontaneous nucleation of bridging cavities as two hydrophobic surfaces approach each other. In both the latter cases, the surfaces will be pulled together through capillary (Laplace pressure) forces (18).…”

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confidence: 99%

Reduced water density at hydrophobic surfaces: Effect of dissolved gases

Doshi

Watkins

Israelachvili

et al. 2005

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

253

264

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Here, direct noninvasive neutron reflectivity measurements reveal the presence of a reduced (deuterated) water density region, with a sigmoidal density profile at the hydrophobic silane-water interface that depends on the type and concentration of dissolved gases in the water. Removal of dissolved gases decreases the width of the reduced water density region, and their reintroduction leads to its increase. When compared with recent computer simulations, a locally fluctuating density profile is proposed, whereas preexisting nanobubbles are excluded. The presence of a fluctuating reduced water density region between two hydrophobic surfaces and the attractive ''depletion force'' to which it leads may help explain the hydrophobic force and its reported diminution in deaerated water. Our results are also quantitatively consistent with recent dynamic surface force apparatus results that drastically revise previous estimates of the slip length of water flowing past hydrophobic surfaces from microns to Ϸ20 nm. Our observations, therefore, go a long way toward reconciling three quite different types of experiments and phenomena: water depletion at hydrophobic surfaces, water slip at hydrophobic surfaces, and the hydrophobic interaction.interfacial water ͉ neutron reflectivity ͉ slip conditions

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“…Follow-up experiments by numerous other investigators also showed the presence of the attractive structural force, which was appropriately referred to as hydrophobic force (Christenson and Claesson, 2001). It was shown that the hydrophobic force increases with increasing water contact angle (Yoon and Ravishankar, 1996). Other investigators showed, on the other hand, that the long-28 range attractions observed with hydrophobic surfaces are actually the capillary forces created by coalescing air bubbles.…”

Section: Introductionmentioning

confidence: 95%

Establishment of the Center for Advanced Separation Technologies

Hull¹

2005

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INTRODUCTIONThe U.S. is the largest producer of mining products in the world. In 1999, U.S. mining operations produced $66.7 billion worth of raw materials that contributed a total of $533 billion to the nation's wealth. Despite these contributions, the mining industry has not been well supported with research and development funds as compared to mining industries in other countries. To overcome this problem, the Center for Advanced Separation Technologies (CAST) was established by Virginia Tech and West Virginia University to develop technologies that can be used by the U.S. mining industry to create new products, reduce production costs, and meet environmental regulations. This endeavor is supported through U.S. DOE Cooperative Agreement No. DE-FC26-01NT41091: Establishment of the Center for Advance Separation Technologies.Much of the research to be carried out at CAST will be longer-term, high-risk, basic research, and will be carried out in four broad areas: a) Solid-solid separation b) Solid-liquid separation c) Chemical/Biological extraction, and d) Sensor and control development.Distribution of funds has been handled via competitive solicitation of research proposals through Site Coordinators at the two universities. Two RFP's have been issued to date. The first of these, referred to as the CAST I -Round 1 RFP, was issued on August 17, 2001 and closed October 15, 2001. A total of 12 proposals were received in response to this first RFP. These were first reviewed and ranked by a group of technical reviewers (selected primarily from industry). Based on these reviews, and an assessment of overall program requirements, the CAST Technical Committee made an initial selection/ranking of proposals and forwarded these proposals to the DOE/NETL Project Officer for final review and approval. This process took some 6 months to complete but 8 projects were in place at the constituent universities (5 at Virginia Tech and three at West Virginia University) by May 17, 2002. This was followed, on June 1, 2002 with the CAST I -Round 2 RFP, which closed on July 19, 2002. A total of 12 proposals were received in response to this second RFPfive were selected for funding. These were in place at the constituent universities (2 at Virginia Tech and 3 at West Virginia University) by March 1, 2003.All thirteen of these projects are listed below by category, along with brief abstracts of their aims and objectives. The recovery of coarse particles by flotation is a common problem in the coal and minerals processing industry. The objective of this project is to develop methods of extending the upper particle size limit for flotation. The availability of such a technology will improve processing efficiency and greatly simplify the plant flowsheet. Two different complementary approaches will be used to achieve the project objective. One is to use novel flotation reagents that will help increase the attachment force between air bubbles and coarse particles, and the other is to develop new flotation machines specifically de...

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Long-Range Hydrophobic Forces between Mica Surfaces in Dodecylammonium Chloride Solutions in the Presence of Dodecanol

Cited by 90 publications

References 17 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

Reduced water density at hydrophobic surfaces: Effect of dissolved gases

Establishment of the Center for Advanced Separation Technologies

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